D-piece modifications of the hemiasterlin analog HTI-286 produce potent tubulin inhibitors.

PubMed

Zask, Arie; Birnberg, Gary; Cheung, Katherine; Kaplan, Joshua; Niu, Chuan; Norton, Emily; Yamashita, Ayako; Beyer, Carl; Krishnamurthy, Girija; Greenberger, Lee M; Loganzo, Frank; Ayral-Kaloustian, Semiramis

2004-08-16

Modifications of the D-piece carboxylic acid group of the hemiasterlin analog HTI-286 gave tubulin inhibitors which were potent cytotoxic agents in taxol resistant cell lines expressing P-glycoprotein. Amides derived from proline had potency comparable to HTI-286. Reduction of the carboxylic acid to ketones and alcohols or its conversion to acidic heterocycles also gave potent analogs. Synthetic modifications of the carboxylic acid could be carried out selectively using a wide range of synthetic reagents. Proline analog 3 was found to be effective in a human xenograft model in athymic mice.

Indium-Catalyzed Reductive Dithioacetalization of Carboxylic Acids with Dithiols: Scope, Limitations, and Application to Oxidative Desulfurization.

PubMed

Nishino, Kota; Minato, Kohei; Miyazaki, Takahiro; Ogiwara, Yohei; Sakai, Norio

2017-04-07

In this study an InI 3 -TMDS (1,1,3,3-tetramethyldisiloxane) reducing system effectively catalyzed the reductive dithioacetalization of a variety of aromatic and aliphatic carboxylic acids with 1,2-ethanedithiol or 1,3-propanedithiol leading to the one-pot preparation of either 1,3-dithiolane derivatives or a 1,3-dithiane derivative. Also, the intact indium catalyst continuously catalyzed the subsequent oxidative desulfurization of an in situ formed 1,3-dithiolane derivative, which led to the preparation of the corresponding aldehydes.

The Effects of Benzofuran-2-Carboxylic Acid Derivatives as Countermeasures in Immune Modulation and Cancer Cell Inhibition

NASA Astrophysics Data System (ADS)

Sundaresan, A.; Marriott, K.; Mao, J.; Bhuiyan, S.; Denkins, P.

2015-06-01

Microgravity and radiation exposure experienced during space flights result in immune system suppression. In long-term spaceflight, the crew is exposed to space radiation, microgravity, infectious agents from other crew members, and microbial contamination, all of which have a significant impact on the body's immune system and may contribute to the development of autoimmune diseases, allergic reactions, and/or cancer initiation. Many studies have revealed strong effects of microgravity on immune cell function, and microgravity is now considered as one of the major causes of immune dysfunction during space flight (Sundaresan, Int. J. Transp. Phenom. 12(1-2), 93-100, 2011; Martinelli et al., IEEE Eng. Biol. Med. 28(4), 85-90, 2009). We screened two newly synthetized derivatives of benzofuran 2-carboxylic acid, KMEG and KM12. The former KMEG was assessed for lymphoproliferative activities while the latter, KM12, was used in an array of cancer cell lines for testing its cancer inhibiting effects. For ground-based studies, synthetic benzofuran-2-carboxylic acid derivatives were assessed for biological effects in several scenarios, which involved exposure to modeled microgravity and radiation, as well as their immune enhancement and anti-cancer effects. Initial findings indicate that the benzofuran-2-carboxylic acid derivatives possibly have immune enhancing and anti-tumor properties in human lymphocytes and cancer cells exposed to analog spaceflight conditions modeled microgravity and γ-radiation).

Design of co-crystals/salts of some Nitrogenous bases and some derivatives of thiophene carboxylic acids through a combination of hydrogen and halogen bonds.

PubMed

Jennifer, Samson Jegan; Muthiah, Packianathan Thomas

2014-01-01

The utility of N-heterocyclic bases to obtain molecular complexes with carboxylic acids is well studied. Depending on the solid state interaction between the N-heterocyclic base and a carboxylic acid a variety of neutral or ionic synthons are observed. Meanwhile, pyridines and pyrimidines have been frequently chosen in the area of crystal engineering for their multipurpose functionality. HT (hetero trimers) and LHT (linear heterotetramers) are the well known synthons that are formed in the presence of pyrimidines and carboxylic acids. Fourteen crystals involving various substituted thiophene carboxylic acid derivatives and nitrogenous bases were prepared and characterized by using single crystal X-ray diffraction. The 14 crystals can further be divided into two groups [1a-7a], [8b-14b] based on the nature of the nitrogenous base. Carboxylic acid to pyridine proton transfer has occurred in 3 compounds of each group. In addition to the commonly occurring hydrogen bond based pyridine/carboxylic acid and pyrimidine/carboxylic acid synthons which is the reason for assembly of primary motifs, various other interactions like Cl…Cl, Cl…O, C-H…Cl, C-H…S add additional support in organizing these supermolecules into extended architectures. It is also interesting to note that in all the compounds π-π stacking occurs between the pyrimidine-pyrimidine or pyridine-pyridine or acid-acid moieties rather than acid-pyrimidine/pyridine. In all the compounds (1a-14b) either neutral O-H…Npyridyl/pyrimidine or charge-assisted Npyridinium-H…Ocarboxylate hydrogen bonds are present. The HT (hetero trimers) and LHT (linear heterotetramers) are dominant in the crystal structures of the adducts containing N-heterocyclic bases with two proton acceptors (1a-7a). Similar type supramolecular ladders are observed in 5TPC44BIPY (8b), TPC44BIPY (9b), TPC44TMBP (11b). Among the seven compounds [8b-14b] the extended ligands are linear in all except for the TMBP (10b, 11b, 12b). The structure of each compound depends on the dihedral angle between the carboxyl group and the nitrogenous base. All these compounds indicate three main synthons that regularly occur, namely linear heterodimer (HD), heterotrimer (HT) and heterotetramer (LHT).

Enantioselective Synthesis of α-Methylene-β-hydroxy Carboxylic Acid Derivatives via a Diastereoselective Aldol-β-Elimination Sequence: Application to the C(15)–C(21) Fragment of Tedanolide C

PubMed Central

Barth, Roland; Roush, William R.

2010-01-01

An enantioselective synthesis of α-methylene-β-hydroxy carboxylic acid derivatives via a highly diastereoselective, one-pot syn-aldol and β-elimination sequence utilizing the chiral β-(phenylselenyl)propionyl imide 15 is described. This new method, which constitutes an alternative to the Baylis-Hillman reaction, has been applied to the synthesis of the C(15)-C(21) fragment of tedanolide C. PMID:20405855

A library synthesis of 4-hydroxy-3-methyl-6-phenylbenzofuran-2-carboxylic acid ethyl ester derivatives as anti-tumor agents.

PubMed

Hayakawa, Ichiro; Shioya, Rieko; Agatsuma, Toshinori; Furukawa, Hidehiko; Naruto, Shunji; Sugano, Yuichi

2004-09-06

As a result of a hit-to-lead program using a technique of solution-phase parallel synthesis, a highly potent (2,4-dimethoxyphenyl)-[6-(3-fluorophenyl)-4-hydroxy-3-methylbenzofuran-2-yl]methanone (15b) was synthesized as an optimized derivative of 4-hydroxy-3-methyl-6-phenylbenzofuran-2-carboxylic acid ethyl ester (1), which was discovered as a screening hit from small-molecule libraries and exhibited selective cytotoxicity against a tumorigenic cell line.

Hydrogenation of carbonyl compounds of relevance to hydrogen storage in alcohols

NASA Astrophysics Data System (ADS)

Suárez, Andrés

2018-02-01

Alcohols are a promising source for the sustainable production of hydrogen that may also serve as rechargeable liquid organic hydrogen carriers (LOHCs). Metal-catalyzed acceptorless dehydrogenation of alcohols produces carbonyl derivatives as H2-depleted by-products, which by means of a hydrogenation reaction can be reconverted to the initial alcohols. Hence, reversible H2-storage systems based on pairs of secondary alcohols/ketones and primary alcohols/carboxylic acid derivatives may be envisaged. In this contribution, the hydrogenation of carbonyl derivatives, including ketones, esters, amides and carboxylic acids, is reviewed from the perspective of the hydrogen storage in alcohols.

Synthesis and anticandidal activity of some imidazopyridine derivatives.

PubMed

Kaplancikli, Zafer Asim; Turan-Zitouni, Gülhan; Ozdemir, Ahmet; Revial, Gilbert

2008-12-01

New hydrazide derivatives of imidazo[1,2-a]pyridine have been synthesized and evaluated for anticandidal activity. The reaction of imidazo[1,2-a]pyridine-2-carboxylic acid hydrazides with various benzaldehydes gave N-(benzylidene)imidazo[ 1,2-a]pyridine-2-carboxylic acid hydrazide derivatives. Their anticandidal activities against Candida albicans and Candida glabrata (isolates obtained from Osmangazi University, Faculty of Medicine, Eskisehir, Turkey), Candida albicans (ATCC 90028), Candida utilis (NRLL Y-900), Candida tropicalis (NRLL Y-12968), Candida krusei (NRLL Y-7179), Candida zeylanoides (NRLL Y-1774), and Candida parapsilosis (NRLL Y-12696) were investigated.

A tandem conjugate addition/cyclization protocol for the asymmetric synthesis of 2-aryl-4-aminotetrahydroquinoline-3-carboxylic acid derivatives.

PubMed

Davies, Stephen G; Mujtaba, Nadeam; Roberts, Paul M; Smith, Andrew D; Thomson, James E

2009-05-07

Condensation of tert-butyl (E)-3-(2'-aminophenyl)propenoate with a range of aromatic and heteroaromatic aldehydes gives the corresponding imines as single diastereoisomers (>98% de). Addition of lithium (R)-N-benzyl-N-(alpha-methylbenzyl)amide initiates a tandem conjugate addition/cyclization reaction to generate 2-aryl-4-aminotetrahydroquinoline-3-carboxylic acid derivatives in >98% de, >98% ee and high isolated yield. Hydrogenolysis of an N(1)-Boc protected derivative allows selective cleavage of the N-benzyl-N-alpha-methylbenzyl protecting groups without compromise of the diastereo- or enantiopurity.

Development of Matrix Metalloproteinase-2 Inhibitors for Cardioprotection

PubMed Central

Bencsik, Péter; Kupai, Krisztina; Görbe, Anikó; Kenyeres, Éva; Varga, Zoltán V.; Pálóczi, János; Gáspár, Renáta; Kovács, László; Weber, Lutz; Takács, Ferenc; Hajdú, István; Fabó, Gabriella; Cseh, Sándor; Barna, László; Csont, Tamás; Csonka, Csaba; Dormán, György; Ferdinandy, Péter

2018-01-01

The objective of our present study is to develop novel inhibitors for MMP-2 for acute cardioprotection. In a series of pilot studies, novel substituted carboxylic acid derivatives were synthesized based on imidazole and thiazole scaffolds and then tested in a screeening cascade for MMP inhibition. We found that the MMP-inhibiting effects of imidazole and thiazole carboxylic acid-based compounds are superior in efficacy in comparison to the conventional hydroxamic acid derivatives of the same molecules. Based on these results, a 568-membered focused library of imidazole and thiazole compounds was generated in silico and then the library members were docked to the 3D model of MMP-2 followed by an in vitro medium throughput screening (MTS) based on a fluorescent assay employing MMP-2 catalytic domain. Altogether 45 compounds showed a docking score of >70, from which 30 compounds were successfully synthesized. Based on the MMP-2 inhibitory tests using gelatin zymography, 7 compounds were then selected and tested in neonatal rat cardiac myocytes subjected to simulated I/R injury. Six compounds showed significant cardio-cytoprotecion and the most effective compound (MMPI-1154) significantly decreased infarct size when applied at 1 μM in an ex vivo model for acute myocardial infarction. This is the first demonstration that imidazole and thiazole carboxylic acid-based compounds are more efficacious MMP-2 inhibitor than their hydroxamic acid derivatives. MMPI-1154 is a promising novel cardio-cytoprotective imidazole-carboxylic acid MMP-2 inhibitor lead candidate for the treatment of acute myocardial infarction. PMID:29674965

Sulfur-containing constituents and one 1H-pyrrole-2-carboxylic acid derivative from pineapple [Ananas comosus (L.) Merr.] fruit.

PubMed

Zheng, Zong-Ping; Ma, Jinyu; Cheng, Ka-Wing; Chao, Jianfei; Zhu, Qin; Chang, Raymond Chuen-Chung; Zhao, Ming; Lin, Zhi-Xiu; Wang, Mingfu

2010-12-01

Two sulfur-containing compounds, (S)-2-amino-5-((R)-1-carboxy-2-((E)-3-(4-hydroxy-3-methoxyphenyl)allylthio)ethyl-amino)-5-oxopentanoic acid (1) and (S)-2-amino-5-((R)-1-(carboxymethylamino)-3-((E)-3-(4-hydroxyphenyl)allylthio)-1-oxopropan-2-ylamino)-5-oxopentanoic acid (2), and one 1H-pyrrole-2-carboxylic acid derivative, 6-(3-(1H-pyrrole-2-carbonyloxy)-2-hydroxypropoxy)-3,4,5-trihydroxy-tetrahydro-2H-pyran-2-carboxylic acid (3), together with eighteen known phenolic compounds, were isolated from the fruits of pineapple. Their structures were elucidated by a combination of spectroscopic analyses. Some of these compounds showed inhibitory activities against tyrosinase. The half maximal inhibitory concentration values of compounds 1, 4, 5, 6, 7 are lower than 1 mM. These compounds may contribute to the well-known anti-browning effect of pineapple juice and be potential skin whitening agents in cosmetic applications. Copyright © 2010 Elsevier Ltd. All rights reserved.

Application of L-proline derivatives as chiral shift reagents for enantiomeric recognition of carboxylic acids.

PubMed

Naziroglu, Hayriye Nevin; Durmaz, Mustafa; Bozkurt, Selahattin; Sirit, Abdulkadir

2011-07-01

Four proline-derived chiral receptors 5-8 were readily synthesized starting from L-proline. The enantiomeric recognition ability of chiral receptors was examined with a series of carboxylic acids by (1) H NMR spectroscopy. The molar ratio and the association constants of the chiral compounds with each of the enantiomers of guest molecules were determined by using Job plots and a nonlinear least-squares fitting method, respectively. The Job plots indicate that the hosts form 1:1 instantaneous complexes with all guests. The receptors exhibited different chiral recognition abilities toward the enantiomers of racemic guests. Among the chiral receptors used in this study, prolinamide 6 was found to be the best chiral shift reagent and is effective for the determination of the enantiomeric excess of chiral carboxylic acids. Copyright © 2011 Wiley-Liss, Inc.

The effects of borate minerals on the synthesis of nucleic acid bases, amino acids and biogenic carboxylic acids from formamide.

PubMed

Saladino, Raffaele; Barontini, Maurizio; Cossetti, Cristina; Di Mauro, Ernesto; Crestini, Claudia

2011-08-01

The thermal condensation of formamide in the presence of mineral borates is reported. The products afforded are precursors of nucleic acids, amino acids derivatives and carboxylic acids. The efficiency and the selectivity of the reaction was studied in relation to the elemental composition of the 18 minerals analyzed. The possibility of synthesizing at the same time building blocks of both genetic and metabolic apparatuses, along with the production of amino acids, highlights the interest of the formamide/borate system in prebiotic chemistry.

Surface Patterning of Benzene Carboxylic Acids on Graphite: Influence of structure, solvent, and concentration on molecular self-assembly

NASA Astrophysics Data System (ADS)

Florio, Gina; Stiso, Kimberly; Campanelli, Joseph; Dessources, Kimberly; Folkes, Trudi

2012-02-01

Scanning tunneling microscopy (STM) was used to investigate the molecular self-assembly of four different benzene carboxylic acid derivatives at the liquid/graphite interface: pyromellitic acid (1,2,4,5-benzenetetracarboxylic acid), trimellitic acid (1,2,4-benzenetricarboxylic acid), trimesic acid (1,3,5-benzenetricarboxylic acid), and 1,3,5-benzenetriacetic acid. A range of two dimensional networks are observed that depend sensitively on the number of carboxylic acids present, the nature of the solvent, and the solution concentration. We will describe our recent efforts to determine (a) the preferential two-dimensional structure(s) for each benzene carboxylic acid at the liquid/graphite interface, (b) the thermodynamic and kinetic factors influencing self-assembly (or lack thereof), (c) the role solvent plays in the assembly, (e) the effect of in situ versus ex situ dilution on surface packing density, and (f) the temporal evolution of the self-assembled monolayer. Results of computational analysis of analog molecules and model monolayer films will also be presented to aid assignment of network structures and to provide a qualitative picture of surface adsorption and network formation.

Aromatic Prenylation in Phenazine Biosynthesis

PubMed Central

Saleh, Orwah; Gust, Bertolt; Boll, Björn; Fiedler, Hans-Peter; Heide, Lutz

2009-01-01

The bacterium Streptomyces anulatus 9663, isolated from the intestine of different arthropods, produces prenylated derivatives of phenazine 1-carboxylic acid. From this organism, we have identified the prenyltransferase gene ppzP. ppzP resides in a gene cluster containing orthologs of all genes known to be involved in phenazine 1-carboxylic acid biosynthesis in Pseudomonas strains as well as genes for the six enzymes required to generate dimethylallyl diphosphate via the mevalonate pathway. This is the first complete gene cluster of a phenazine natural compound from streptomycetes. Heterologous expression of this cluster in Streptomyces coelicolor M512 resulted in the formation of prenylated derivatives of phenazine 1-carboxylic acid. After inactivation of ppzP, only nonprenylated phenazine 1-carboxylic acid was formed. Cloning, overexpression, and purification of PpzP resulted in a 37-kDa soluble protein, which was identified as a 5,10-dihydrophenazine 1-carboxylate dimethylallyltransferase, forming a C–C bond between C-1 of the isoprenoid substrate and C-9 of the aromatic substrate. In contrast to many other prenyltransferases, the reaction of PpzP is independent of the presence of magnesium or other divalent cations. The Km value for dimethylallyl diphosphate was determined as 116 μm. For dihydro-PCA, half-maximal velocity was observed at 35 μm. Kcat was calculated as 0.435 s-1. PpzP shows obvious sequence similarity to a recently discovered family of prenyltransferases with aromatic substrates, the ABBA prenyltransferases. The present finding extends the substrate range of this family, previously limited to phenolic compounds, to include also phenazine derivatives. PMID:19339241

4-Hydroxy-3-methyl-6-phenylbenzofuran-2-carboxylic acid ethyl ester derivatives as potent anti-tumor agents.

PubMed

Hayakawa, Ichiro; Shioya, Rieko; Agatsuma, Toshinori; Furukawa, Hidehiko; Naruto, Shunji; Sugano, Yuichi

2004-01-19

Based on the structure of 4-hydroxy-3-methyl-6-phenylbenzofuran-2-carboxylic acid ethyl ester (1), which exhibits selective cytotoxicity against a tumorigenic cell line, (2,4-dimethoxyphenyl)-(4-hydroxy-3-methyl-6-phenylbenzofuran-2-yl)-methanone (18m) was designed and synthesized as a biologically stable derivative containing no ester group. Although the potency of 18m was almost the same as our initial hit compound 1, 18m is expected to last longer in the human body as an anticancer agent.

Aristolic Acid Derivatives from the Bark of Antidesma ghaesembilla.

PubMed

Schäfer, Sibylle; Schwaiger, Stefan; Stuppner, Hermann

2017-08-01

Antidesma ghaesembilla is an important medicinal and food plant in many Asian countries. Ten substances could be isolated from the dichloromethane and methanol extract: sitostenone ( 3 ), daucosterol ( 4 ), chavibetol ( 5 ), asperphenamate ( 6 ), protocatechuic acid ( 7 ), vanillic acid-4- O - β -D-glucoside ( 8 ), 1- O - β -D-glucopyranosyl-3- O -methyl-phloroglucinol ( 9 ), and aristolic acid II-8- O - β -D-glucoside ( 10 ), and two new aristolic acid derivatives, 10-amino-5,7-dimethoxy-aristolic acid II (= 6-amino-9,11-dimethoxyphenanthro[3,4- d ]-1,3-dioxole-5-carboxylic acid; 1 ) and 5,7-dimethoxy-aristolochic acid II (= 9,11-dimethoxy-6-nitrophenantro[3,4- d ]-1,3-dioxole-5-carboxylic acid; 2 ). Exposure to humans of some of these compounds is associated with a severe disease today known as aristolochic acid nephropathy. Therefore, the traditional usage of this plant has to be reconsidered carefully. Georg Thieme Verlag KG Stuttgart · New York.

[Chloroquine analogues from benzofuro- and benzothieno[3,2-b]-4-pyridone-2-carboxylic acid esters].

PubMed

Gölitzer, K; Meyer, H; Jomaa, H; Wiesner, J

2004-08-01

The amides 7 were synthesized from the annulated methyl 4-pyridone-2-carboxylates 4 via the carboxylic acids 5 and their acid chlorides by reacting with the novaldiamine base 6. The alcohol 8b, obtained from DIBAH reduction of the ester 4b, was transformed to the chloromethyl derivative 9 which reacted with 6 and 18-crown-6 leading to the 2-novaldiaminomethyl-4-pyridone 10. Compound 10 was obtained with higher yield from DIBAH reduction of the amide 7b. The substances 7 and 10 were inactive when tested against the chloroquine resistant Plasmodium falciparum strain Dd2.

Beyond ketonization: selective conversion of carboxylic acids to olefins over balanced Lewis acid–base pairs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baylon, Rebecca A. L.; Sun, Junming; Martin, Kevin J.

Dwindling petroleum reserves combined with increased energy demand and political factors encouraging an increase in energy independence have led to a large amount of research on sustainable alternatives. To this end, biomass conversion has been recognized as themost readily viable technology to produce biofuel concerning our reliance on liquid fuels for transportation and has the advantage of being easily integrated into our heavy use of combustion engines. The interest in biomass conversion has also resulted in reduced costs and a greater abundance of bio-oil, a mixture of hundreds of oxygenates including alcohols, aldehydes, carboxylic acids, and ketones. However, the presencemore » of carboxylic acids in bio-oil derived from lignocellulose pyrolysis leads to low pH, instability, and corrosiveness. In addition, carboxylic acids (i.e. acetic acid) can also be produced via fermentation of sugars. This can be accomplished by a variety of homoacetogenic microorganisms that can produce acetic acid with 100% carbon yield.« less

New derivatives of 3,4-dihydroisoquinoline-3-carboxylic acid with free-radical scavenging, D-amino acid oxidase, acetylcholinesterase and butyrylcholinesterase inhibitory activity.

PubMed

Solecka, Jolanta; Guśpiel, Adam; Postek, Magdalena; Ziemska, Joanna; Kawęcki, Robert; Lęczycka, Katarzyna; Osior, Agnieszka; Pietrzak, Bartłomiej; Pypowski, Krzysztof; Wyrzykowska, Agata

2014-09-30

A series of 3,4-dihydroisoquinoline-3-carboxylic acid derivatives were synthesised and tested for their free-radical scavenging activity using 2,2-diphenyl-1-picrylhydrazyl radical (DPPH·), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical (ABTS·+), superoxide anion radical (O2·-) and nitric oxide radical (·NO) assays. We also studied d-amino acid oxidase (DAAO), acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitory activity. Almost each of newly synthesised compounds exhibited radical scavenging capabilities. Moreover, several compounds showed moderate inhibitory activities against DAAO, AChE and BuChE. Compounds with significant free-radical scavenging activity may be potential candidates for therapeutics used in oxidative-stress-related diseases.

Synthesis, spectroscopic characterization, biological screenings, DNA binding study and POM analyses of transition metal carboxylates.

PubMed

Uddin, Noor; Sirajuddin, Muhammad; Uddin, Nizam; Tariq, Muhammad; Ullah, Hameed; Ali, Saqib; Tirmizi, Syed Ahmed; Khan, Abdur Rehman

2015-04-05

This article contains the synthesis of a novel carboxylic acid derivative, its transition metal complexes and evaluation of biological applications. Six carboxylate complexes of transition metals, Zn(II) and Hg(II), have been successfully synthesized and characterized by FT-IR and NMR (1H, 13C). The ligand, HL, (4-[(2,6-Diethylphenyl)amino]-4-oxobutanoic acid) was also characterized by single crystal X-ray analysis. The complexation occurs via oxygen atoms of the carboxylate moiety. FT-IR date show the bidentate nature of the carboxylate moiety of the ligand as the Δν value in all complexes is less than that of the free ligand. The ligand and its complexes were screened for antifungal and antileishmanial activities. The results showed that the ligand and its complexes are active with few exceptions. UV-visible spectroscopy and viscometry results reveal that the ligand and its complexes interact with the DNA via intercalative mode of interaction. A new and efficient strategy to identify the pharmacophores and anti-pharmacophores sites in carboxylate derivatives for the antibacterial/antifungal activity using Petra, Osiris and Molinspiration (POM) analyses was also carried out. Copyright © 2014 Elsevier B.V. All rights reserved.

Synthesis, spectroscopic characterization, biological screenings, DNA binding study and POM analyses of transition metal carboxylates

NASA Astrophysics Data System (ADS)

Uddin, Noor; Sirajuddin, Muhammad; Uddin, Nizam; Tariq, Muhammad; Ullah, Hameed; Ali, Saqib; Tirmizi, Syed Ahmed; Khan, Abdur Rehman

2015-04-01

This article contains the synthesis of a novel carboxylic acid derivative, its transition metal complexes and evaluation of biological applications. Six carboxylate complexes of transition metals, Zn(II) and Hg(II), have been successfully synthesized and characterized by FT-IR and NMR (1H, 13C). The ligand, HL, (4-[(2,6-Diethylphenyl)amino]-4-oxobutanoic acid) was also characterized by single crystal X-ray analysis. The complexation occurs via oxygen atoms of the carboxylate moiety. FT-IR date show the bidentate nature of the carboxylate moiety of the ligand as the Δν value in all complexes is less than that of the free ligand. The ligand and its complexes were screened for antifungal and antileishmanial activities. The results showed that the ligand and its complexes are active with few exceptions. UV-visible spectroscopy and viscometry results reveal that the ligand and its complexes interact with the DNA via intercalative mode of interaction. A new and efficient strategy to identify the pharmacophores and anti-pharmacophores sites in carboxylate derivatives for the antibacterial/antifungal activity using Petra, Osiris and Molinspiration (POM) analyses was also carried out.

Factors influencing the rate of non-enzymatic activation of carboxylic and amino acids by ATP

NASA Technical Reports Server (NTRS)

Mullins, D. W., Jr.; Lacey, J. C., Jr.

1981-01-01

The nonenzymatic formation of adenylate anhydrides of carboxylic and amino acids is discussed as a necessary step in the origin of the genetic code and protein biosynthesis. Results of studies are presented which have shown the rate of activation to depend on the pKa of the carboxyl group, the pH of the medium, temperature, the divalent metal ion catalyst, salt concentration, and the nature of the amino acid. In particular, it was found that of the various amino acids investigated, phenylalanine had the greatest affinity for the adenine derivatives adenosine and ATP. Results thus indicate that selective affinities between amino acids and nucleotides were important during prebiotic chemical evolution, and may have played a major role in the origin of protein synthesis and genetic coding.

Waste-free synthesis of condensed heterocyclic compounds by rhodium-catalyzed oxidative coupling of substituted arene or heteroarene carboxylic acids with alkynes.

PubMed

Shimizu, Masaki; Hirano, Koji; Satoh, Tetsuya; Miura, Masahiro

2009-05-01

The direct oxidative coupling of 2-amino- and 2-hydroxybenzoic acids with internal alkynes proceeds efficiently in the presence of a rhodium/copper catalyst system under air to afford the corresponding 8-substituted isocoumarin derivatives, some of which exhibit solid-state fluorescence. Depending on conditions, 4-ethenylcarbazoles can be synthesized selectively from 2-(arylamino)benzoic acids. The oxidative coupling reactions of heteroarene carboxylic acids as well as aromatic diacids with an alkyne are also described.

Analysis of carbonaceous biomarkers with the Mars Organic Analyzer microchip capillary electrophoresis system: carboxylic acids.

PubMed

Stockton, Amanda M; Tjin, Caroline Chandra; Chiesl, Thomas N; Mathies, Richard A

2011-01-01

The oxidizing surface chemistry on Mars argues that any comprehensive search for organic compounds indicative of life requires methods to analyze higher oxidation states of carbon with very low limits of detection. To address this goal, microchip capillary electrophoresis (μCE) methods were developed for analysis of carboxylic acids with the Mars Organic Analyzer (MOA). Fluorescent derivatization was achieved by activation with the water soluble 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) followed by reaction with Cascade Blue hydrazide in 30 mM borate, pH 3. A standard containing 12 carboxylic acids found in terrestrial life was successfully labeled and separated in 30 mM borate at pH 9.5, 20 °C by using the MOA CE system. Limits of detection were 5-10 nM for aliphatic monoacids, 20 nM for malic acid (diacid), and 230 nM for citric acid (triacid). Polyacid benzene derivatives containing 2, 3, 4, and 6 carboxyl groups were also analyzed. In particular, mellitic acid was successfully labeled and analyzed with a limit of detection of 300 nM (5 ppb). Analyses of carboxylic acids sampled from a lava tube cave and a hydrothermal area demonstrated the versatility and robustness of our method. This work establishes that the MOA can be used for sensitive analyses of a wide range of carboxylic acids in the search for extraterrestrial organic molecules. © Mary Ann Liebert, Inc.

Tris[(6S)-6-hy-droxy-4-epi-shikimic acid] monohydrate: an enanti-omerically pure hy-droxy-lated shikimic acid derived from methyl shikimate.

PubMed

Griesbeck, Axel G; Miara, Claus; Neudörfl, Jörg-M

2012-11-01

The title compound, 3C(7)H(10)O(6)·H(2)O, is the enanti-omerically pure product of a multi-step synthesis from the enanti-omerically pure natural shikimic acid. The asymmetric unit contains three mol-ecules of the acid and one mol-ecule of water. The cyclo-hexene rings of the acids have half-chair conformations. The carboxyl-ate, the four hydroxide groups and the additional water mol-ecule form a complex three-dimensional hydrogen-bonding network.

New coumarin carboxylates having trifluoromethyl, diethylamino and morpholino terminal groups: Synthesis and mesomorphic characterisations

NASA Astrophysics Data System (ADS)

Srinivasa, Hosapalya Thimmaiah; Harishkumar, Hosanagara Narayana; Palakshamurthy, Bandrehalli Siddagangappa

2017-03-01

New set of trifluromethyl, diethylamino and morpholino derived coumarin compounds were prepared by reacting various coumarin 3-carboxylic acids with various phenyl esters with peripheral alkyl, ester and polar cyano moieties in the presence of EDC.HCl/DMAP as esterification agent. The chemical structures of new coumarin derivatives were confirmed by standard spectroscopic techniques and mesomorphic behaviours were established by polarised optical microscopy (POM) and differential scanning calorimetry (DSC). Trifluoromethane and morpholino derivatives show SmA/Nematic phase, while diethylamino derivatives did not show liquid crystalline property.

Synthesis and structures of cadmium carboxylate and thiocarboxylate compounds with a sulfur-rich coordination environment: Carboxylate exchange kinetics involving tris(2-mercapto-1- t-butylimidazolyl)hydroborato cadmium complexes, [Tm But]Cd(O 2CR)

DOE PAGES

Kreider-Mueller, Ava; Quinlivan, Patrick J.; Owen, Jonathan S.; ...

2015-03-31

Here, a series of cadmium carboxylate compounds in a sulfur-rich environment provided by the tris(2- tert-butylmercaptoimidazolyl)hydroborato ligand, namely, [Tm But]CdO 2CR, has been synthesized via the reactions of the cadmium methyl derivative [Tm But]CdMe with RCO 2H. Such compounds mimic aspects of cadmium-substituted zinc enzymes and also the surface atoms of cadmium chalcogenide crystals, and have therefore been employed to model relevant ligand exchange processes. Significantly, both 1H and 19F NMR spectroscopy demonstrate that the exchange of carboxylate groups between [Tm But]Cd(κ 2-O 2CR) and the carboxylic acid RCO 2H is facile on the NMR time scale, even at lowmore » temperature. Analysis of the rate of exchange as a function of concentration of RCO 2H indicates that reaction occurs via an associative rather than dissociative pathway. In addition to carboxylate compounds, the thiocarboxylate derivative [Tm But]Cd[κ 1-SC(O)Ph] has also been synthesized via the reaction of [Tm But]CdMe with thiobenzoic acid. The molecular structure of [Tm But]Cd[κ 1-SC(O)Ph] has been determined by X-ray diffraction, and an interesting feature is that, in contrast to the carboxylate derivatives [Tm But]Cd(κ 2-O 2CR), the thiocarboxylate ligand binds in a κ 1 manner via only the sulfur atom.« less

Synthesis and structures of cadmium carboxylate and thiocarboxylate compounds with a sulfur-rich coordination environment: Carboxylate exchange kinetics involving tris(2-mercapto-1- t-butylimidazolyl)hydroborato cadmium complexes, [Tm But]Cd(O 2CR)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kreider-Mueller, Ava; Quinlivan, Patrick J.; Owen, Jonathan S.

Here, a series of cadmium carboxylate compounds in a sulfur-rich environment provided by the tris(2- tert-butylmercaptoimidazolyl)hydroborato ligand, namely, [Tm But]CdO 2CR, has been synthesized via the reactions of the cadmium methyl derivative [Tm But]CdMe with RCO 2H. Such compounds mimic aspects of cadmium-substituted zinc enzymes and also the surface atoms of cadmium chalcogenide crystals, and have therefore been employed to model relevant ligand exchange processes. Significantly, both 1H and 19F NMR spectroscopy demonstrate that the exchange of carboxylate groups between [Tm But]Cd(κ 2-O 2CR) and the carboxylic acid RCO 2H is facile on the NMR time scale, even at lowmore » temperature. Analysis of the rate of exchange as a function of concentration of RCO 2H indicates that reaction occurs via an associative rather than dissociative pathway. In addition to carboxylate compounds, the thiocarboxylate derivative [Tm But]Cd[κ 1-SC(O)Ph] has also been synthesized via the reaction of [Tm But]CdMe with thiobenzoic acid. The molecular structure of [Tm But]Cd[κ 1-SC(O)Ph] has been determined by X-ray diffraction, and an interesting feature is that, in contrast to the carboxylate derivatives [Tm But]Cd(κ 2-O 2CR), the thiocarboxylate ligand binds in a κ 1 manner via only the sulfur atom.« less

Binary Supramolecular Gel of Achiral Azobenzene with a Chaperone Gelator: Chirality Transfer, Tuned Morphology, and Chiroptical Property.

PubMed

Ji, Lukang; Ouyang, Guanghui; Liu, Minghua

2017-10-31

Binary supramolecular gels based on achiral azobenzene derivatives and a chiral chaperone gelator, long-alkyl-chain-substituted L-Histidine (abbreviated as LHC18) that could assist many nongelling acids in forming gels, were investigated in order to fabricate the chiroptical gel materials in a simple way. It was found that although the carboxylic acid-terminated achiral azobenzene derivatives could not form gels in any solvents, when mixed with LHC18 they formed the co-gels and self-assembled into various morphologies ranging from nanotubes and loose nanotubes to nanosheets, depending on the substituent groups on the azobenzene moiety. The ether linkage and the number of carboxylic acid groups attached to the azobenzene moiety played important roles. Upon gel formation, the localized molecular chirality in LHC18 could be transferred to the azobenzene moiety. Combined with the trans-cis isomerization of the azobenzene, optically and chiroptically reversible gels were generated. It was found that the gel based on azobenzene with two carboxylic acid groups and ether linkages showed clear optical reversibility but less chiroptical reversibility, whereas the gel based on azobenzene with one carboxylic acid and an ether linkage showed both optical and chiroptical reversibility. Thus, new insights into the relationship among the molecular structures of the azobenzene, self-assembled nanostructures in the gel and the optical and chiroptical reversibility were disclosed.

Carboxylic acids in crystallization of macromolecules: learning from successful crystallization experiments.

PubMed

Offermann, Lesa R; He, John Z; Mank, Nicholas J; Booth, William T; Chruszcz, Maksymilian

2014-03-01

The production of macromolecular crystals suitable for structural analysis is one of the most important and limiting steps in the structure determination process. Often, preliminary crystallization trials are performed using hundreds of empirically selected conditions. Carboxylic acids and/or their salts are one of the most popular components of these empirically derived crystallization conditions. Our findings indicate that almost 40 % of entries deposited to the Protein Data Bank (PDB) reporting crystallization conditions contain at least one carboxylic acid. In order to analyze the role of carboxylic acids in macromolecular crystallization, a large-scale analysis of the successful crystallization experiments reported to the PDB was performed. The PDB is currently the largest source of crystallization data, however it is not easily searchable. These complications are due to a combination of a free text format, which is used to capture information on the crystallization experiments, and the inconsistent naming of chemicals used in crystallization experiments. Despite these difficulties, our approach allows for the extraction of over 47,000 crystallization conditions from the PDB. Initially, the selected conditions were investigated to determine which carboxylic acids or their salts are most often present in crystallization solutions. From this group, selected sets of crystallization conditions were analyzed in detail, assessing parameters such as concentration, pH, and precipitant used. Our findings will lead to the design of new crystallization screens focused around carboxylic acids.

Stereoselective synthesis of conformationally constrained omega-amino acid analogues from pyroglutamic acid.

PubMed

Bentz, Emilie L; Goswami, Rajesh; Moloney, Mark G; Westaway, Susan M

2005-08-07

Bicyclic lactams derived from pyroglutamic acid provide a useful scaffold for synthesis of conformationally restricted analogues of lysine, ornithine and glutamine, as well as an Ala-Ala dipeptide analogue. Amino alcohol and carboxylic acid derivatives are accessible from a common intermediate. In this strategy, the bicyclic lactam system not only controls, but also facilitates the determination of the stereochemistry of the synthetic intermediates.

Synthesis and Proteasome Inhibition of Glycyrrhetinic Acid Derivatives

PubMed Central

Huang, Li; Yu, Donglei; Ho, Phong; Qian, Keduo; Lee, Kuo-Hsiung; Chen, Chin-Ho

2008-01-01

This study discovered that glycyrrhetinic acid inhibited the human 20S proteasome at 22.3 µM. Esterification of the C-3 hydroxyl group on glycyrrhetinic acid with various carboxylic acid reagents yielded a series of analogs with marked improved potency. Among the derivatives, glycyrrhetinic acid 3-O-isophthalate (17) was the most potent compound with IC50 of 0.22 µM, which was approximately 100-fold more potent than glycyrrhetinic acid. PMID:18562200

Genetic Analysis of Nitroaromatic Degradation by Clostridium

DTIC Science & Technology

2013-07-30

potential Effect on butyrate levels Methylene blue +0.011 no phenazine - 1 - carboxylic acid -0.116 More butyrate TNT -0.253 More butyrate Neutral red -0.325...pattern and possible complications of soil electron mediators on TNT degradation. We observed that phenazine carboxylate was a reasonable derivative to...assessment of the potential for soil communities to degrade TNT. The examined the concentration of phenazine carboxylate required to show a similar

pKa Modulation in rhodamine based probes for colorimetric detection of picric acid.

PubMed

Nagarajan, V; Bag, Bamaprasad

2014-12-21

Tuning the pKa in acid sensitive rhodamine spirolactam derivatives as a function of the solvent medium resulted in the selective detection of picric acid from its lower nitro phenolic analogues and a few other carboxylic acids.

Lewis acid-Lewis acid heterobimetallic cooperative catalysis: mechanistic studies and application in enantioselective aza-Michael reaction.

PubMed

Yamagiwa, Noriyuki; Qin, Hongbo; Matsunaga, Shigeki; Shibasaki, Masakatsu

2005-09-28

The full details of a catalytic asymmetric aza-Michael reaction of methoxylamine promoted by rare earth-alkali metal heterobimetallic complexes are described, demonstrating the effectiveness of Lewis acid-Lewis acid cooperative catalysis. First, enones were used as substrates, and the 1,4-adducts were obtained in good yield (57-98%) and high ee (81-96%). Catalyst loading was successfully reduced to 0.3-3 mol % with enones. To broaden the substrate scope of the reaction to carboxylic acid derivatives, alpha,beta-unsaturated N-acylpyrroles were used as monodentate, carboxylic acid derivatives. With beta-alkyl-substituted N-acylpyrroles, the reaction proceeded smoothly and the products were obtained in high yield and good ee. Transformation of the 1,4-adducts from enones and alpha,beta-unsaturated N-acylpyrroles afforded corresponding chiral aziridines and beta-amino acids. Detailed mechanistic studies, including kinetics, NMR analysis, nonlinear effects, and rare earth metal effects, are also described. The Lewis acid-Lewis acid cooperative mechanism, including the substrate coordination mode, is discussed in detail.

Synthesis of some 1,8-dioxoacridine carboxylic acid derivatives and the determination of their ionization constants in ethanol-water mixtures

NASA Astrophysics Data System (ADS)

Saygılı, Rukiye; Ulus, Ramazan; Yeşildağ, İbrahim; Kübra İnal, E.; Kaya, Muharrem; Murat Kalfa, O.; Zeybek, Bülent

2015-03-01

Four novel compounds of 1,8-dioxoacridine carboxylic acid derivatives (4-(3,3,6,6-tetramethyl-1,8-dioxo-9-phenyl-1,2,3,4,5,6,7,8-octahydroacridin-10(9H)-yl)benzoic acid, 4-(9-(4-cyanophenyl)-3,3,6,6-tetramethyl-1,8-dioxo-1,2,3,4,5,6,7,8-octahydroacridin-10(9H)-yl)benzoic acid, 4-(9-(4-hydroxyphenyl)-3,3,6,6-tetramethyl-1,8-dioxo-1,2,3,4,5,6,7,8-octahydroacridin-10(9H)-yl)benzoic acid, 4-(9-(2,4-dichlorophenyl)-3,3,6,6-tetramethyl-1,8-dioxo-1,2,3,4,5,6,7,8-octahydroacridin-10(9H)-yl)benzoic acid) were prepared by the reaction of the 4-substitute benzaldehyde (hydrogen, hydroxyl, cyano, and 2,4-dichloro), 4-aminobenzoic acid, and 5,5-dimethylcyclohexane-1,3-dione in the presence of p-dodecylbenzenesulfonic acid. They were characterized by using FT-IR, 1H-NMR, 13C-NMR, GC-MS spectroscopic techniques. The stoichiometric ionization constants of these compounds were determined in ethanol-water mixtures of 50%, 60% and 70% ethanol (v/v) by potentiometric titration method and the ionization constants were calculated with three different ways. The effects of solvent composition and substituent groups on ionization constants of 1,8-dioxoacridine carboxylic acids were also discussed.

Triterpenoids and Prevention of Prostate Cancer

DTIC Science & Technology

2001-10-01

synthesized various oleanolic and oleanane and ursane triterpenoids. 4 We have therefore ursolic acid derivatives and tested them as inhibitors considered that...1) of novel olean-12-ene triterpenoids with a 1-en-3-one and ursolic acid (2), which are commercially available, functionality having carboxyl...enone derivatives of oleanolic acid and ursolic acid as inhibitors of nitric 28-oic acid (3) had the highest activity (IC5o = 0.07 pM) oxide production

Determination of the conformation of 2-hydroxy- and 2-aminobenzoic acid dimers using 13C NMR and density functional theory/natural bond order analysis: the central importance of the carboxylic acid carbon.

PubMed

Burnette, Ronald R; Weinhold, Frank

2006-07-20

The 13C chemical shift for the carboxylic acid carbon provides a powerful diagnostic probe to determine the preferred isomeric dimer structures of benzoic acid derivatives undergoing intra- and intermolecular H-bonding in the gas, solution and crystalline phases. We have employed hybrid density functional calculations and natural bond orbital analysis to elucidate the electronic origins of the observed 13C shieldings and their relationship to isomeric stability. We find that delocalizing interactions from the carbonyl oxygen lone pairs (nO) into vicinal carbon-oxygen and carbon-carbon antibonds (sigmaCO*,sigmaCC*) make critical contributions to the 13C shieldings, and these nO --> sigmaCO*, nO --> sigmaCC* interactions are in turn sensitive to the intramolecular interactions that dictate dimer structure and stability. The carboxyl carbon atom can thus serve as a useful detector of subtle structural and conformational features in this pharmacologically important class of carboxylic acid interactions.

Characterization of some amino acid derivatives of benzoyl isothiocyanate: Crystal structures and theoretical prediction of their reactivity

NASA Astrophysics Data System (ADS)

Odame, Felix; Hosten, Eric C.; Betz, Richard; Lobb, Kevin; Tshentu, Zenixole R.

2015-11-01

The reaction of benzoyl isothiocyanate with L-serine, L-proline, D-methionine and L-alanine gave 2-[(benzoylcarbamothioyl)amino]-3-hydroxypropanoic acid (I), 1-(benzoylcarbamothioyl)pyrrolidine-2-carboxylic acid (II), 2-[(benzoylcarbamothioyl)amino]-4-(methylsulfanyl)butanoic acid (III) and 2-[(benzoylcarbamothioyl)amino]propanoic acid (IV), respectively. The compounds have been characterized by IR, NMR, microanalyses and mass spectrometry. The crystal structures of all the compounds have also been discussed. Compound II showed rotamers in solution. DFT calculations of the frontier orbitals of the compounds have been carried out to ascertain the groups that contribute to the HOMO and LUMO, and to study their contribution to the reactivity of these compounds. The calculations indicated that the carboxylic acid group in these compounds is unreactive hence making the conversion to benzimidazoles via cyclization on the carboxylic acids impractical. This has been further confirmed by the reaction of compounds I-IV, respectively, with o-phenylene diamine which was unsuccessful but gave compound V.

Antimicrobial activities, DNA interactions, spectroscopic (FT-IR and UV-Vis) characterizations, and DFT calculations for pyridine-2-carboxylic acid and its derivates

NASA Astrophysics Data System (ADS)

Tamer, Ömer; Tamer, Sevil Arabacı; İdil, Önder; Avcı, Davut; Vural, Hatice; Atalay, Yusuf

2018-01-01

In this paper, pyridine- 2- carboxylic acid, also known as picolinic acid (pic), and its two derivate, 4- methoxy-pyridine- 2- carboxylic acid (4-Mpic) and 4- chloro-pyridine- 2- carboxylic acid (4-Clpic) have been characterized by FT-IR and UV-Vis spectroscopy techniques as well as DFT calculations. B3LYP level of Density Functional Theory (DFT) method was used to obtain ground state geometries, vibration wavenumbers, first order hyperpolarizabilities and molecular electrostatic potential (MEP) surfaces for pic, 4Clpic and 4Mpic. The electronic absorption wavelengths and HOMO-LUMO energies were investigated by time dependent B3LYP (TD-B3LYP) level with the conductor-like polarizable continuum model (CPCM). The effects of Cl atom and OCH3 group on HOMO-LUMO energy gaps and first order hyperpolarizability parameters of pic, 4Clpic and 4Mpic molecules were examined. All molecules were screened for their antibacterial activities against Gram-positive and Gram-negative bacteria and for their antifungal activities against yeast strains by using minimal inhibitory concentration method (MIC). All compounds (pic, 4Mpic and 4Clpic) have been found to be very active against to the Gram (+) and Gram (-) bacteria. The DNA interactions of pic, 4Clpic and 4Mpic were analyzed by molecular docking simulations, and the interaction of the 4Mpic molecule with DNA is found to be higher than 4Clpic and pic.

Mass spectrometric analysis of L-cysteine metabolism: physiological role and fate of L-cysteine in the enteric protozoan parasite Entamoeba histolytica.

PubMed

Jeelani, Ghulam; Sato, Dan; Soga, Tomoyoshi; Watanabe, Haruo; Nozaki, Tomoyoshi

2014-11-04

L-cysteine is essential for virtually all living organisms, from bacteria to higher eukaryotes. Besides having a role in the synthesis of virtually all proteins and of taurine, cysteamine, glutathione, and other redox-regulating proteins, L-cysteine has important functions under anaerobic/microaerophilic conditions. In anaerobic or microaerophilic protozoan parasites, such as Entamoeba histolytica, L-cysteine has been implicated in growth, attachment, survival, and protection from oxidative stress. However, a specific role of this amino acid or related metabolic intermediates is not well understood. In this study, using stable-isotope-labeled L-cysteine and capillary electrophoresis-time of flight mass spectrometry, we investigated the metabolism of L-cysteine in E. histolytica. [U-(13)C3, (15)N]L-cysteine was rapidly metabolized into three unknown metabolites, besides L-cystine and L-alanine. These metabolites were identified as thiazolidine-4-carboxylic acid (T4C), 2-methyl thiazolidine-4-carboxylic acid (MT4C), and 2-ethyl-thiazolidine-4-carboxylic acid (ET4C), the condensation products of L-cysteine with aldehydes. We demonstrated that these 2-(R)-thiazolidine-4-carboxylic acids serve for storage of L-cysteine. Liberation of L-cysteine occurred when T4C was incubated with amebic lysates, suggesting enzymatic degradation of these L-cysteine derivatives. Furthermore, T4C and MT4C significantly enhanced trophozoite growth and reduced intracellular reactive oxygen species (ROS) levels when it was added to cultures, suggesting that 2-(R)-thiazolidine-4-carboxylic acids are involved in the defense against oxidative stress. Amebiasis is a human parasitic disease caused by the protozoan parasite Entamoeba histolytica. In this parasite, L-cysteine is the principal low-molecular-weight thiol and is assumed to play a significant role in supplying the amino acid during trophozoite invasion, particularly when the parasites move from the anaerobic intestinal lumen to highly oxygenated tissues in the intestine and the liver. It is well known that E. histolytica needs a comparatively high concentration of L-cysteine for its axenic cultivation. However, the reason for and the metabolic fate of L-cysteine in this parasite are not well understood. Here, using a metabolomic and stable-isotope-labeled approach, we investigated the metabolic fate of this amino acid in these parasites. We found that L-cysteine inside the cell rapidly reacts with aldehydes to form 2-(R)-thiazolidine-4-carboxylic acid. We showed that these 2-(R)-thiazolidine-4-carboxylic derivatives serve as an L-cysteine source, promote growth, and protect cells against oxidative stress by scavenging aldehydes and reducing the ROS level. Our findings represent the first demonstration of 2-(R)-thiazolidine-4-carboxylic acids and their roles in protozoan parasites. Copyright © 2014 Jeelani et al.

Impact of Macroporosity on Catalytic Upgrading of Fast Pyrolysis Bio-Oil by Esterification over Silica Sulfonic Acids.

PubMed

Manayil, Jinesh C; Osatiashtiani, Amin; Mendoza, Alvaro; Parlett, Christopher M A; Isaacs, Mark A; Durndell, Lee J; Michailof, Chrysoula; Heracleous, Eleni; Lappas, Angelos; Lee, Adam F; Wilson, Karen

2017-09-11

Fast pyrolysis bio-oils possess unfavorable physicochemical properties and poor stability, in large part, owing to the presence of carboxylic acids, which hinders their use as biofuels. Catalytic esterification offers an atom- and energy-efficient route to upgrade pyrolysis bio-oils. Propyl sulfonic acid (PrSO 3 H) silicas are active for carboxylic acid esterification but suffer mass-transport limitations for bulky substrates. The incorporation of macropores (200 nm) enhances the activity of mesoporous SBA-15 architectures (post-functionalized by hydrothermal saline-promoted grafting) for the esterification of linear carboxylic acids, with the magnitude of the turnover frequency (TOF) enhancement increasing with carboxylic acid chain length from 5 % (C 3 ) to 110 % (C 12 ). Macroporous-mesoporous PrSO 3 H/SBA-15 also provides a two-fold TOF enhancement over its mesoporous analogue for the esterification of a real, thermal fast-pyrolysis bio-oil derived from woodchips. The total acid number was reduced by 57 %, as determined by GC×GC-time-of-flight mass spectrometry (GC×GC-ToFMS), which indicated ester and ether formation accompanying the loss of acid, phenolic, aldehyde, and ketone components. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

α-Amino Acid-Isosteric α-Amino Tetrazoles

PubMed Central

Zhao, Ting; Kurpiewska, Katarzyna; Kalinowska-Tłuścik, Justyna; Herdtweck, Eberhardt

2016-01-01

The synthesis of all 20 common natural proteinogenic and 4 otherα-amino acid-isosteric α-amino tetrazoles has been accomplished, whereby the carboxyl group is replaced by the isosteric 5-tetrazolyl group. The short process involves the use of the key Ugi tetrazole reaction followed by deprotection chemistries. The tetrazole group is bioisosteric to the carboxylic acid and is widely used in medicinal chemistry and drug design. Surprisingly, several of the common α-amino acid-isosteric α-amino tetrazoles are unknown up to now. Therefore a rapid synthetic access to this compound class and non-natural derivatives is of high interest to advance the field. PMID:26817531

Synthesis of carboxylic acids, esters, alcohols and ethers containing a tetrahydropyran ring derived from 6-methyl-5-hepten-2-one.

PubMed

Hanzawa, Yohko; Hashimoto, Kahoko; Kasashima, Yoshio; Takahashi, Yoshiko; Mino, Takashi; Sakamoto, Masami; Fujita, Tsutomu

2012-01-01

3-hydroxy acids, 3-hydroxy-3,7-dimethyloct-6-enoic acid (1) and 3-hydroxy-2,2,3,7-tetramethyloct-6-enoic acid (2), were prepared from 6-methyl-5-hepten-2-one, and they were subsequently used to prepare (2,6,6-trimethyltetrahydropyran-2-yl)acetic acid (3) and 2-methyl-2-(2,6,6-trimethyltetrahydropyran-2-yl)propanoic acid (4), respectively, via cyclization with an acidic catalyst such as boron trifluoride diethyl etherate or iodine. The reaction of carboxylic acids 3 and 4 with alcohols, including methanol, ethanol, and 1-propanol, produced the corresponding methyl, ethyl, and propyl esters, which all contained a tetrahydropyran ring. Reduction of carboxylic acids 3 and 4 afforded the corresponding alcohols. Subsequent reactions of these alcohols with several acyl chlorides produced novel esters. The alcohols also reacted with methyl iodide and sodium hydride to provide novel ethers. A one-pot cyclization-esterification of 1 to produce esters containing a tetrahydropyran ring, using iodine as a catalyst, was also investigated.

Theoretical study of the thermodynamics of the mechanisms underlying antiradical activity of cinnamic acid derivatives.

PubMed

Amić, Ana; Marković, Zoran; Klein, Erik; Dimitrić Marković, Jasmina M; Milenković, Dejan

2018-04-25

The role of antiradical moieties (catechol, guaiacyl and carboxyl group) and molecular conformation in antioxidative potency of dihydrocaffeic acid (DHCA) and dihydroferulic acid (DHFA) was investigated by density functional theory (DFT) method. The thermodynamic preference of different reaction paths of double (2H + /2e - ) free radical scavenging mechanisms was estimated. Antiradical potency of DHCA and DHFA was compared with that exerted by their unsaturated analogs - caffeic acid (CA) and ferulic acid (FA). Cis/trans and anti-isomers of studied cinnamic acid derivatives may scavenge free radicals via double processes by involvement of catechol or guaiacyl moiety. Carboxyl group of syn-isomers may also participate in the inactivation of free radicals. Gibbs free energies of reactions with various free radicals indicate that syn-DHCA and syn-DHFA, colon catabolites that could be present in systemic circulation in low μM concentrations, have a potential to contribute to health benefits by direct free radical scavenging. Copyright © 2017 Elsevier Ltd. All rights reserved.

Efficient synthesis of anacardic acid analogues and their antibacterial activities.

PubMed

Mamidyala, Sreeman K; Ramu, Soumya; Huang, Johnny X; Robertson, Avril A B; Cooper, Matthew A

2013-03-15

Anacardic acid derivatives exhibit a broad range of biological activities. In this report, an efficient method for the synthesis of anacardic acid derivatives was explored, and a small set of salicylic acid variants synthesised retaining a constant hydrophobic element (a naphthyl tail). The naphthyl side chain was introduced via Wittig reaction and the aldehyde installed using directed ortho-metalation reaction of the substituted o-anisic acids. The failure of ortho-metalation using unprotected carboxylic acid group compelled us to use directed ortho-metalation in which a tertiary amide was used as a strong ortho-directing group. In the initial route, tertiary amide cleavage during final step was challenging, but cleaving the tertiary amide before Wittig reaction was beneficial. The Wittig reaction with protected carboxylic group (methyl ester) resulted in side-products whereas using sodium salt resulted in higher yields. The novel compounds were screened for antibacterial activity and cytotoxicity. Although substitution on the salicylic head group enhanced antibacterial activities they also enhanced cytotoxicity. Copyright © 2013 Elsevier Ltd. All rights reserved.

Synthesis, structures, electrochemical studies and antioxidant activity of 5-aryl-4-oxo-3,4,5,8-tetrahydropyrido[2,3-d]pyrimidine-7-carboxylic acids

NASA Astrophysics Data System (ADS)

Quiroga, Jairo; Romo, Pablo E.; Ortiz, Alejandro; Isaza, José Hipólito; Insuasty, Braulio; Abonia, Rodrigo; Nogueras, Manuel; Cobo, Justo

2016-09-01

The synthesis of 5-aryl-4-oxo-3,4,5,8-tetrahydropyrido[2,3-d]pyrimidine-7-carboxylic acids 3 from the reaction of 6-aminopyrimidines 1 with arylidene derivatives of pyruvic acid 2 under microwave and ultrasound irradiation is described. The orientation of cyclization process was determined by NMR measurements. The methodology provides advantages such as high yields and friendly to the environment without the use of solvents. The antioxidant properties, DPPH free radical scavenging, ORAC, and anodic potential oxidation of the new pyridopyrimidines were studied.

Gas-Phase Amidation of Carboxylic Acids with Woodward’s Reagent K Ions

PubMed Central

Peng, Zhou; Pilo, Alice L.; Luongo, Carl A.; McLuckey, Scott A.

2015-01-01

Gas-phase amidation of carboxylic acids in multiply-charged peptides is demonstrated via ion/ion reactions with Woodward’s reagent K (wrk) in both positive and negative mode. Woodward’s reagent K, N-ethyl-3-phenylisoxazolium-3′-sulfonate, is a commonly used reagent that activates carboxylates to form amide bonds with amines in solution. Here, we demonstrate that the analogous gas-phase chemistry occurs upon reaction of the wrk ions and doubly protonated (or doubly deprotonated) peptide ions containing the carboxylic acid functionality. The reaction involves the formation of the enol ester intermediate in the electrostatic complex. Upon collisional activation, the ethyl amine on the reagent is transferred to the activated carbonyl carbon on the peptide, resulting in the formation of an ethyl amide (addition of 27 Da to the peptide) with loss of a neutral ketene derivative. Further collision-induced dissociation (CID) of the products and comparison with solution-phase amidation product confirms the structure of the ethyl amide. PMID:26122523

Simultaneous determination of C1-C4 carboxylic acids and aldehydes using 2,4-dinitrophenylhydrazine-impregnated silica gel and high-performance liquid chromatography.

PubMed

Uchiyama, Shigehisa; Matsushima, Erika; Aoyagi, Shohei; Ando, Masanori

2004-10-01

A new method for the simultaneous determination of aliphatic carboxylic acids and aldehydes in air is described. In this work, carboxylic acids were allowed to react with 2,4-dinitrophenylhydrazine (DNPH) to form the corresponding carboxylic 2,4-dinitrophenylhydrazides. These derivatives have excellent thermal stability, with melting points higher than those of the corresponding hydrazones by 32-50 degrees C. C1-C4 carboxylic acid 2,4-dinitrophenylhydrazides exhibited maximum absorption wavelengths of 331-334 nm and molar absorption coefficients of 1.4 x 10(4) L/mol/cm. They were completely separated by high-performance liquid chromatography (HPLC) with an RP-Amide C16 column. Cartridges packed with DNPH-coated silica particles (DNPH cartridge) were used for sampling formic acid and aldehydes. Formic acid was physically adsorbed on the silica particles as the first step of the sampling mechanism. Gradual reaction with DNPH followed. Formic acid reacted very slowly with DNPH at room temperature (20 degrees C), but reacted completely at 80 degrees C over 4 h. In field measurements, the sample air was drawn through a DNPH cartridge. After sampling, the cartridges were heated at 80 degrees C for 5 h and extracted with acetonitrile for HPLC analysis. Under these optimized conditions, the LOD is 0.4 ug/m(3) for an air sample collected for 24 h at 100 mL/min (144 L).

Saccharomyces cerevisiae sigma 1278b has novel genes of the N-acetyltransferase gene superfamily required for L-proline analogue resistance.

PubMed

Takagi, H; Shichiri, M; Takemura, M; Mohri, M; Nakamori, S

2000-08-01

We discovered on the chromosome of Saccharomyces cerevisiae Sigma 1278b novel genes involved in L-proline analogue L-azetidine-2-carboxylic acid resistance which are not present in the standard laboratory strains. The 5.4 kb-DNA fragment was cloned from the genomic library of the L-azetidine-2-carboxylic acid-resistant mutant derived from a cross between S. cerevisiae strains S288C and Sigma 1278b. The nucleotide sequence of a 4.5-kb segment exhibited no identity with the sequence in the genome project involving strain S288C. Deletion analysis indicated that one open reading frame encoding a predicted protein of 229 amino acids is indispensable for L-azetidine-2-carboxylic acid resistance. The protein sequence was found to be a member of the N-acetyltransferase superfamily. Genomic Southern analysis and gene disruption showed that two copies of the novel gene with one amino acid change at position 85 required for L-azetidine-2-carboxylic acid resistance were present on chromosomes X and XIV of Sigma 1278b background strains. When this novel MPR1 or MPR2 gene (sigma 1278b gene for L-proline analogue resistance) was introduced into the other S. cerevisiae strains, all of the recombinants were resistant to L-azetidine-2-carboxylic acid, indicating that both MPR1 and MPR2 are expressed and have a global function in S. cerevisiae.

High Throughput Synthesis and Screening for Agents Inhibiting Androgen Receptor Mediated Gene Transcription

DTIC Science & Technology

2005-02-01

hydrochloride salt and methyl ester hydrolysis of 244 (LiOH, THF-MeOH) provided the lithium carboxylate Pyrrolidine based system (2a and b). Several hydro...strategy detailed above, the lithium salt 26 was used to provide trimer 28 (Scheme 4). However, coupling of the carboxylic acid derived from 28 with 3...M. A. Chem. Ind. 1996, 68, 325. 1. (a) Dervan, P. B. Bioorg. Med. Chem. 2001, 9, 2215. (b) 13. The lithium salt 26 was used instead of the carboxylic

Perfluoroalkyl acids and related chemistries Toxicokinetics and modes of action

EPA Science Inventory

The perfluoroalkyl acid salts (both carboxylates and sulfonates, hereafter designated as PFAAs) and their derivatives are important chemicals that have numerous consumer and industrial applications. However, recent discoveries that some of these compounds have global distribution...

Electrochemistry and spectroelectrochemistry of bioactive hydroxyquinolines: a mechanistic study.

PubMed

Sokolová, Romana; Nycz, Jacek E; Ramešová, Šárka; Fiedler, Jan; Degano, Ilaria; Szala, Marcin; Kolivoška, Viliam; Gál, Miroslav

2015-05-21

The oxidation mechanism of selected hydroxyquinoline carboxylic acids such as 8-hydroxyquinoline-7-carboxylic acid (1), the two positional isomers 2-methyl-8-hydroxyquinoline-7-carboxylic acid (3) and 2-methyl-5-hydroxyquinoline-6-carboxylic acid (4), as well as other hydroxyquinolines were studied in aprotic environment using cyclic voltammetry, controlled potential electrolysis, in situ UV-vis and IR spectroelectrochemistry, and HPLC-MS/MS techniques. IR spectroelectrochemistry showed that oxidation unexpectedly proceeds together with protonation of the starting compound. We proved that the nitrogen atom in the heterocycle of hydroxyquinolines is protonated during the apparent 0.7 electron oxidation process. This was rationalized by the autodeprotonation reaction by another two starting molecules of hydroxyquinoline, so that the overall oxidation mechanism involves two electrons and three starting molecules. Both the electrochemical and spectroelectrochemical results showed that the oxidation mechanism is not influenced by the presence of the carboxylic group in the chemical structure of hydroxyquinolines, as results from oxidation of 2,7-dimethyl-5-hydroxyquinoline (6). In the presence of a strong proton acceptor such as pyridine, the oxidation ECEC process involves two electrons and two protons per one molecule of the hydroxyquinoline derivative. The electron transfer efficiency of hydroxyquinolines in biosystems may be related to protonation of biocompounds containing nitrogen bases. Molecular orbital calculations support the experimental findings.

A Precise Method for Processing Data to Determine the Dissociation Constants of Polyhydroxy Carboxylic Acids via Potentiometric Titration.

PubMed

Huang, Kaixuan; Xu, Yong; Lu, Wen; Yu, Shiyuan

2017-12-01

The thermodynamic dissociation constants of xylonic acid and gluconic acid were studied via potentiometric methods, and the results were verified using lactic acid, which has a known pKa value, as a model compound. Solutions of xylonic acid and gluconic acid were titrated with a standard solution of sodium hydroxide. The determined pKa data were processed via the method of derivative plots using computer software, and the accuracy was validated using the Gran method. The dissociation constants associated with the carboxylic acid group of xylonic and gluconic acids were determined to be pKa 1  = 3.56 ± 0.07 and pKa 1  = 3.74 ± 0.06, respectively. Further, the experimental data showed that the second deprotonation constants associated with a hydroxyl group of each of the two acids were pKa 2  = 8.58 ± 0.12 and pKa 2  = 7.06 ± 0.08, respectively. The deprotonation behavior of polyhydroxy carboxylic acids was altered using various ratios with Cu(II) to form complexes in solution, and this led to proposing a hypothesis for further study.

Synthesis and characterisation of hetero-bimetallic organometallic phenylalanine and PNA monomer derivatives.

PubMed

Gasser, Gilles; Brosch, Oliver; Ewers, Alexandra; Weyhermüller, Thomas; Metzler-Nolte, Nils

2009-06-14

The rational, sequential synthesis of two hetero-bimetallic derivatives of the amino acid phenylalanine and one thymine (T) peptide nucleic acid (PNA) monomer is reported. Ferrocene carboxylic acid and (eta-ethene)bis(triphenylphosphine)platinum(0) were successfully reacted with propargylamide amino acid (1a and 1b) or a T PNA monomer derivative (6) to give the expected three bimetallic compounds 4a, 4b and 9 in good yield. An enzymatic route using cross-linked enzyme crystals (CLEC) of subtilopeptidase A in organic solvents gave the ferrocene carboxylate phenylalanine propargylamide precursor (Fc-CO-Phe-NH-CH(2)-CCH, 3a) in comparable yield and purity to the traditional deprotection-peptide coupling sequence. (31)P NMR spectra of these bioorganometallics showed two doublets with (195)Pt satellites corresponding to two chemically different (31)P atoms. Interestingly, in the case of the T PNA monomer derivative 9, these signals were also doubled in a 60 : 40 ratio as a consequence of the existence of two slowly interconverting isomers in solution. Furthermore, the single-crystal X-ray structures of 3a and the hetero-bimetallic phenylalanine derivative 4b were determined, showing the presence of the two organometallics moieties separated by ca. 8.5 A in 4b as well as illustrating the stability of such compounds.

Friedel-Crafts Acylation with Amides

PubMed Central

Raja, Erum K.; DeSchepper, Daniel J.; Nilsson Lill, Sten O.; Klumpp, Douglas A.

2012-01-01

Friedel-Crafts acylation has been known since the 1870s and it is an important organic synthetic reaction leading to aromatic ketone products. Friedel-Crafts acylation is usually done with carboxylic acid chlorides or anhydrides while amides are generally not useful substrates in these reactions. Despite being the least reactive carboxylic acid derivative, we have found a series of amides capable of providing aromatic ketones in good yields (55–96%, 17 examples). We propose a mechanism involving diminished C-N resonance through superelectrophilic activation and subsequent cleavage to acyl cations. PMID:22690740

Ethyl 7-hydroxycoumarin-3-carboxylate derivatives: Synthesis, characterization and effect of liquid crystal properties

NASA Astrophysics Data System (ADS)

Srinivasa, H. T.; Palakshamurthy, B. S.; Mohammad, AbdulKarim-Talaq

2018-03-01

Two sets of new ethyl 7-hydroxycoumarin-3-carboxylate derivatives were synthesized and characterized to study the liquid crystalline properties. Chemical structures were confirmed by IR, NMR, CHN analysis techniques. Mesomarphic properties were accomplished by DSC, POM and X-ray studies. Density functional theory calculations and photophysical studies also performed. In the first set, smaller homologues of alkoxybenzoic acid derivatives exhibit monotropic smectic A (SmA) and higher homologous exhibit enantiotropic smectic A mesophase. The second set alkyl biphenyl derivatives exhibit stable SmA and nematic (N) mesophases. The well defined focal conic texture for SmA and threaded texture for nematic mesophases have been observed.

Studies on quinolone antibacterials. V. Synthesis and antibacterial activity of chiral 5-amino-7-(4-substituted-3-amino-1-pyrrolidinyl)-6- fluoro-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylic acids and derivatives.

PubMed

Yoshida, T; Yamamoto, Y; Orita, H; Kakiuchi, M; Takahashi, Y; Itakura, M; Kado, N; Yasuda, S; Kato, H; Itoh, Y

1996-07-01

We previously demonstrated that 5-amino-7-(3-amino-1-pyrrolidinyl) -1-cyclopropyl-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylic acid (7) has strong in vitro antibacterial activity even against quinolone-resistant bacteria. We examined optimization of the 3-aminopyrrolidine moiety of 7 by introduction of C-alkyl (Me, Et, Pr, di-Me, cyclopropyl) and N-alkyl groups (Me, di-Me). C-Alkylation at the 4-position of the 3-aminopyrrolidine moiety enhanced in vitro and in vivo antibacterial activity. (S)-5-Amino-7-(7-amino-5-azaspiro[2.4]hept-5-yl)-1-cyclopropyl-pyr rolidinyl) -1-cyclopropyl-6-fluoro-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylic acid (15b) showed strong antibacterial activity (in vitro antibacterial activity including quinolone-resistant bacteria is 4 times more potent than that of ciprofloxacin (CPFX) (1); in vivo antibacterial activity is 1.5 to 20 times more potent than that of CPFX (1)) and reduced quinolone toxicity (free from both phototoxicity at a dosage of 30 mg/kg in guinea pigs (i.v.) and convulsion when coadministered with 4-biphenylacetic acid at a dosage of 20 micrograms in rats (i.c.v.)). Their selectivity between DNA topoisomerase II (derived from eukaryotic cells) and DNA gyrase (derived from bacterial cells) was about 3000-fold.

Perfluoroalkyl acids: recent research highlights | Science ...

EPA Pesticide Factsheets

Perfluorinated compounds are organic chemicals in which all hydrogen molecules of the carbon-chain are substituted by fluorine molecules. Generally, there are two types of perfluorinated compounds, the perfluoroalkanes that are primarily used clinically for oxygenation and respiratory ventilation, and the perfluoroalkyl acids (PFAAs). Environmentally relevant PFAAs are a family of about 30 chemicals that consist of a carbon backbone typically 4-14 molecules in length and a charged functional group composed of either sulfonates, carboxylates or phosphonates (and to a lesser extent, phosphinates). While many (>100) derivatives ofPFAAs (such as alcohols, amides, esters and acids) are used for industrial and consumer applications, they can be degraded or metabolized to PFAAs as end-stage products. Thus, PFAAs, rather than their intermediates or derivatives, have drawn the most public attention and research interest. The most widely known PFAAs are the eight-carbon (C8) sulfonate (perfluorooctane sulfonate, PFOS) and carboxylate (perfluorooctanoic acid, PFOA), although the C4 (perfluorobutane) and C6 (perfluorohexane) sulfonates, as well as the C4, C6 and C9 (perfluorononanoic) carboxylates have also been used in commerce. The perfluoroalkyl phosphonates (PFPAs) are fairly new entities for this class ofchemicals. They are typically used as leveling and wetting agents, and defoaming additives in the production of pesticides. They were considered biologically inert by

Pathway diversity leads to 2D-nanostructure in photo-triggered supramolecular assembly.

PubMed

Ghosh, Suhrit; Pal, Deep Sankar

2018-03-31

This communication reports photo-triggered supramolecular assembly of a naphthalene-diimide (NDI) derivative, appended with a photo-labile ortho-nitrobenzyl (ONB)-ester protected carboxylic acid. Photo-irradiation produces the free COOH group which facilitates H-bonding driven face-to-face stacking of the NDI chromophores producing an ultra-thin (height < 2.0 nm) two-dimensional (2D) nano-sheet. In contrast, spontaneous supramolecular assembly of the same active monomer exhibits entirely different features such as uncontrolled growth, J-aggregation and fibrillar morphology. A completely different pathway for photo-triggered assembly is attributed to the dual function of the photo-caged pro-monomer in (i) producing the carboxylic acid in controlled manner and (ii) simultaneously inhibiting the spontaneous J-aggregation of the photo-generated monomers by ester-carboxylic acid H-bonding and in turn directing a distinct growth mechanism. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gas phase absorption studies of photoactive yellow protein chromophore derivatives.

PubMed

Rocha-Rinza, Toms; Christiansen, Ove; Rajput, Jyoti; Gopalan, Aravind; Rahbek, Dennis B; Andersen, Lars H; Bochenkova, Anastasia V; Granovsky, Alexander A; Bravaya, Ksenia B; Nemukhin, Alexander V; Christiansen, Kasper Lincke; Nielsen, Mogens Brøndsted

2009-08-27

Photoabsorption spectra of deprotonated trans p-coumaric acid and two of its methyl substituted derivatives have been studied in gas phase both experimentally and theoretically. We have focused on the spectroscopic effect of the location of the two possible deprotonation sites on the trans p-coumaric acid which originate to either a phenoxide or a carboxylate. Surprisingly, the three chromophores were found to have the same absorption maximum at 430 nm, in spite of having different deprotonation positions. However, the absorption of the chromophore in polar solution is substantially different for the distinct deprotonation locations. We also report on the time scales and pathways of relaxation after photoexcitation for the three photoactive yellow protein chromophore derivatives. As a result of these experiments, we could detect the phenoxide isomer within the deprotonated trans p-coumaric acid in gas phase; however, the occurrence of the carboxylate is uncertain. Several computational methods were used simultaneously to provide insights and assistance in the interpretation of our experimental results. The calculated excitation energies S(0)-S(1) are in good agreement with experiment for those systems having a negative charge on a phenoxide moiety. Although our augmented multiconfigurational quasidegenerate perturbation theory calculations agree with experiment in the description of the absorption spectrum of anions with a carboxylate functional group, there are some puzzling disagreements between experiment and some calculational methods in the description of these systems.

Ozone-induced changes in natural organic matter (NOM) structure

USGS Publications Warehouse

Westerhoff, P.; Debroux, J.; Aiken, G.; Amy, G.

1999-01-01

Hydrophobic organic acids (combined humic and fulvic acids), obtained from an Antarctic Lake with predominantly microbially derived organic carbon sources and two US fiver systems with terrestrial organic carbon sources, were ozonated. Several analyses, including 13C-NMR, UV absorbance, fluorescence, hydrophobic/transphilic classification, and potentiometric titrations, were performed before and after ozonation. Ozonation reduced aromatic carbon content, selectively reducing phenolic carbon content. Ozonation of the samples resulted in increased aliphatic, carboxyl, plus acetal and ketal anomeric carbon content and shifted towards less hydrophobic compounds.Hydrophobic organic acids (combined humic and fulvic acids), obtained from an Antarctic Lake with predominantly microbially derived organic carbon sources and two US river systems with terrestrial organic carbon sources, were ozonated. Several analyses, including 13C-NMR, UV absorbance, fluorescence, hydrophobic/transphilic classification, and potentiometric titrations, were performed before and after ozonation. Ozonation reduced aromatic carbon content, selectively reducing phenolic carbon content. Ozonation of the samples resulted in increased aliphatic, carboxyl, plus acetal and ketal anomeric carbon content and shifted towards less hydrophobic compounds.

PQQ: Biosynthetic studies in Methylobacterium AM1 and Hyphomicrobium X using specific TC labeling and NMR. [Pyrroloquinoline quinones

DOE Office of Scientific and Technical Information (OSTI.GOV)

Houck, D.R.; Hanners, J.L.; Unkefer, C.J.

Using TC labeling and NMR spectroscopy we have determined biosynthetic precursors of pyrroloquinoline quinone (PQQ) in two closely related serine-type methylotrophs, Methylobacterium AM1 and Hyphomicrobium X. Analysis of the TC-labeling data revealed that PQQ is constructed from two amino acids: the portion containing N-6, C-7,8,9 and the two carboxylic acid groups, C-7' and 9', is derived-intact-from glutamate. The remaining portion is derived from tyrosine; the phenol side chain provides the six carbons of the ring containing the orthoquinone, whereas internal cyclization of the amino acid backbone forms the pyrrole-2-carboxylic acid moiety. This is analogous to the cyclization of dopaquinone tomore » form dopachrome. Dopaquinone is a product of the oxidation of tyrosine (via dopa) in reactions catalyzed by monophenol monooxygenase (EC 1.14.18.1). Starting with tyrosine and glutamate, we will discuss possible biosynthetic routes to PQQ. 29 refs., 4 figs., 2 tabs.« less

Hydrogen bonded binary molecular adducts derived from exobidentate N-donor ligand with dicarboxylic acids: Acid⋯imidazole hydrogen-bonding interactions in neutral and ionic heterosynthons

NASA Astrophysics Data System (ADS)

Kathalikkattil, Amal Cherian; Damodaran, Subin; Bisht, Kamal Kumar; Suresh, Eringathodi

2011-01-01

Four new binary molecular compounds between a flexible exobidentate N-heterocycle and a series of dicarboxylic acids have been synthesized. The N-donor 1,4-bis(imidazol-1-ylmethyl)benzene (bix) was reacted with flexible and rigid dicarboxylic acids viz., cyclohexane-1,4-dicarboxylic acid (H 2chdc), naphthalene-1,4-dicarboxylic acid (H 2npdc) and 1H-pyrazole-3,5-dicarboxylic acid (H 2pzdc), generating four binary molecular complexes. X-ray crystallographic investigation of the molecular adducts revealed the primary intermolecular interactions carboxylic acid⋯amine (via O-H⋯N) as well as carboxylate⋯protonated amine (via N-H +⋯O -) within the binary compounds, generating layered and two-dimensional sheet type H-bonded networks involving secondary weak interactions (C-H⋯O) including the solvent of crystallization. Depending on the differences in p Ka values of the selected base/acid (Δp Ka), diverse H-bonded supramolecular assemblies could be premeditated. This study demonstrates the H-bonding interactions between imidazole/imidazolium cation and carboxylic acid/carboxylate anion in providing sufficient driving force for the directed assembly of binary molecular complexes. In the two-component solid form of hetero synthons involving bix and dicarboxylic acid, only H 2chdc exist as cocrystal with bix, while all the other three compounds crystallized exclusively as salt, in agreement with the Δp Ka values predicted for the formation of salts/cocrystals from the base and acid used in the synthesis of supramolecular solids.

Glutamic acid as anticancer agent: An overview

PubMed Central

Dutta, Satyajit; Ray, Supratim; Nagarajan, K.

2013-01-01

The objective of the article is to highlight various roles of glutamic acid like endogenic anticancer agent, conjugates to anticancer agents, and derivatives of glutamic acid as possible anticancer agents. Besides these emphases are given especially for two endogenous derivatives of glutamic acid such as glutamine and glutamate. Glutamine is a derivative of glutamic acid and is formed in the body from glutamic acid and ammonia in an energy requiring reaction catalyzed by glutamine synthase. It also possesses anticancer activity. So the transportation and metabolism of glutamine are also discussed for better understanding the role of glutamic acid. Glutamates are the carboxylate anions and salts of glutamic acid. Here the roles of various enzymes required for the metabolism of glutamates are also discussed. PMID:24227952

Glutamic acid as anticancer agent: An overview.

PubMed

Dutta, Satyajit; Ray, Supratim; Nagarajan, K

2013-10-01

The objective of the article is to highlight various roles of glutamic acid like endogenic anticancer agent, conjugates to anticancer agents, and derivatives of glutamic acid as possible anticancer agents. Besides these emphases are given especially for two endogenous derivatives of glutamic acid such as glutamine and glutamate. Glutamine is a derivative of glutamic acid and is formed in the body from glutamic acid and ammonia in an energy requiring reaction catalyzed by glutamine synthase. It also possesses anticancer activity. So the transportation and metabolism of glutamine are also discussed for better understanding the role of glutamic acid. Glutamates are the carboxylate anions and salts of glutamic acid. Here the roles of various enzymes required for the metabolism of glutamates are also discussed.

Mass Spectrometric Analysis of l-Cysteine Metabolism: Physiological Role and Fate of l-Cysteine in the Enteric Protozoan Parasite Entamoeba histolytica

PubMed Central

Jeelani, Ghulam; Sato, Dan; Soga, Tomoyoshi; Watanabe, Haruo

2014-01-01

ABSTRACT l-Cysteine is essential for virtually all living organisms, from bacteria to higher eukaryotes. Besides having a role in the synthesis of virtually all proteins and of taurine, cysteamine, glutathione, and other redox-regulating proteins, l-cysteine has important functions under anaerobic/microaerophilic conditions. In anaerobic or microaerophilic protozoan parasites, such as Entamoeba histolytica, l-cysteine has been implicated in growth, attachment, survival, and protection from oxidative stress. However, a specific role of this amino acid or related metabolic intermediates is not well understood. In this study, using stable-isotope-labeled l-cysteine and capillary electrophoresis-time of flight mass spectrometry, we investigated the metabolism of l-cysteine in E. histolytica. [U-13C3, 15N]l-cysteine was rapidly metabolized into three unknown metabolites, besides l-cystine and l-alanine. These metabolites were identified as thiazolidine-4-carboxylic acid (T4C), 2-methyl thiazolidine-4-carboxylic acid (MT4C), and 2-ethyl-thiazolidine-4-carboxylic acid (ET4C), the condensation products of l-cysteine with aldehydes. We demonstrated that these 2-(R)-thiazolidine-4-carboxylic acids serve for storage of l-cysteine. Liberation of l-cysteine occurred when T4C was incubated with amebic lysates, suggesting enzymatic degradation of these l-cysteine derivatives. Furthermore, T4C and MT4C significantly enhanced trophozoite growth and reduced intracellular reactive oxygen species (ROS) levels when it was added to cultures, suggesting that 2-(R)-thiazolidine-4-carboxylic acids are involved in the defense against oxidative stress. PMID:25370494

Simultaneous determination of diastereoisomeric and enantiomeric impurities in SSS-octahydroindole-2-carboxylic acid by chiral high-performance liquid chromatography with pre-column derivatization.

PubMed

Wang, Jin Zhao; Zeng, Su; Hu, Gong Yun; Wang, Dan Hua

2009-04-10

SSS-Octahydroindole-2-carboxylic acid (SSS-Oic) is a key intermediate used in the synthesis of some angiotensin-converting enzyme (ACE) inhibitors. The separation of diastereoisomers and enantiomers of Oic was performed using a pre-column derivatization chiral HPLC method. Phenyl isothiocyanate (PITC) was used as the derivatization reagent. Three PITC derivatives of Oic stereoisomers were separated on an Ultron ES-OVM chiral column (150 mm x 4.6 mm, 5 microm). Derivatization conditions such as reaction temperature, reaction time and derivatization reagent concentration were investigated. The chromatographic conditions for separation of the three PITC-Oic derivatives were optimized. The method was successfully applied in the diastereoisomeric and enantiomeric purity test of SSS-Oic.

Gas chromatographic-mass spectrometric investigation of n-alkanes and carboxylic acids in bottom sediments of the northern Caspian Sea

NASA Astrophysics Data System (ADS)

Kenzhegaliev, Akimgali; Zhumagaliev, Sagat; Kenzhegalieva, Dina; Orazbayev, Batyr

2018-03-01

Prior to the start of experimental oil production in the Kashagan field (northern part of the Caspian Sea), n-alkanes and carboxylic acids contained in samples obtained from bottom sediments in the area of artificial island "D" were investigated by gas chromatography-mass spectrometry. Concentrations of 10 n-alkanes (composed of C10-C13, C15-C20) and 11 carboxylic acids (composed of C6-C12, C14-C16) were identified and measured. Concentrations of individual alkanes and carboxylic acids in bottom sediments of the various samples varied between 0.001 ÷ 0.88 μg/g and 0.001 ÷ 1.94 μg/g, respectively. Mass spectra, in particular the M+ molecular ion peak and the most intense peaks of fragment ions, are given. The present study illustrates the stability of molecular ions to electronic ionisation and the main fragment ions to the total ion current and shows that the initial fragmentation of alkanes implies radical cleavage of C2H5 rather than CH3. All aliphatic monocarboxylic acids studied were characterised by McLafferty rearrangement leading to the formation of F4 cation-radical with m/z 60 and F3 cation-radical with m/z 88 in the case of ethylhexanoic acid. The formation of oxonium ions presents another important aspect of acid fragmentation. Using mass numbers of oxonium ions and rearrangement ions allows determination of the substitution character in α- and β- C atoms. The essence of our approach is to estimate the infiltration of hydrocarbon fluids from the enclosing formation into sea water, comprising an analysis of derivatives of organic compounds in bottom sediments. Thus, concentrations of derived organic molecules can serve as a basis for estimates of the depth at which hydrocarbon fluids leak, i.e., to serve as an auxiliary technique in the search for hydrocarbon deposits and to repair well leaks.

Nitroxyl-mediated oxidation of lignin and polycarboxylated products

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stahl, Shannon S.; Rafiee, Mohammad

Methods of selectively modifying lignin, polycarboxylated products thereof, and methods of deriving aromatic compounds therefrom. The methods comprise electrochemically oxidizing lignin using stable nitroxyl radicals to selectively oxidize primary hydroxyls on .beta.-O-4 phenylpropanoid units to corresponding carboxylic acids while leaving the secondary hydroxyls unchanged. The oxidation results in polycarboxylated lignin in the form of a polymeric .beta.-hydroxy acid. The polymeric .beta.-hydroxy acid has a high loading of carboxylic acid and can be isolated in acid form, deprotonated, and/or converted to a salt. The .beta.-hydroxy acid, anion, or salt can also be subjected to acidolysis to generate various aromatic monomers ormore » oligomers. The initial oxidation of lignin to the polycarboxylated form renders the lignin more susceptible to acidolysis and thereby enhances the yield of aromatic monomers and oligomers obtained through acidolysis.« less

Protonation of carboxyl groups in EuDOTA-tetraamide complexes results in catalytic prototropic exchange and quenching of the CEST signal

NASA Astrophysics Data System (ADS)

Zhang, Lei; Evbuomwan, Osasere M.; Tieu, Michael; Zhao, Piyu; Martins, Andre F.; Sherry, A. Dean

2017-10-01

The CEST properties of EuDOTA-tetraamide complexes bearing pendant carboxylate and carboxyl ethyl esters were measured as a function of pH. The CEST signal from the Eu3+-bound water molecule decreased in intensity between pH 8.5 and 4.5 while the proton exchange rates (kex) increased over this same pH range. In comparison, the CEST signal in the corresponding carboxyl ester derivatives was nearly constant. Both observations are consistent with stepwise protonation of the four carboxylic acid groups over this same pH range. This indicates that negative charges on the carboxyl groups above pH 6 facilitate the formation of a strong hydrogen-bonding network in the coordination second sphere above the single Eu3+-bound water molecule, thereby decreasing prototropic exchange of protons on the bound water molecule with bulk water protons. The percentage of square antiprismatic versus twisted square antiprism coordination isomers also decreased as the appended carboxylic acid groups were positioned further away from the amide. The net effect of lowering the pH was an overall increase in kex and a quenching of the CEST signal. This article is part of the themed issue 'Challenges for chemistry in molecular imaging'.

Saponification of esters of chiral alpha-amino acids anchored through their amine function on solid support.

PubMed

Cantel, Sonia; Desgranges, Stéphane; Martinez, Jean; Fehrentz, Jean-Alain

2004-06-01

Anchoring an alpha-amino acid residue by its amine function onto a solid support is an alternative to develop chemistry on its carboxylic function. This strategy can involve the use of amino-acid esters as precursors of the carboxylic function. A complete study on the Wang-resin was performed to determine the non racemizing saponification conditions of anchored alpha-amino esters. The use of LiOH, NaOH, NaOSi(Me)3, various solvents and temperatures were tested for this reaction. After saponification and cleavage from the support, samples were examined through their Marfey's derivatives by reversed phase HPLC to evaluate the percentage of racemization.

Separation of aromatic carboxylic acids using quaternary ammonium salts on reversed-phase HPLC. 1. Separation behavior of aromatic carboxylic acids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kawamura, K.; Okuwaki, A.; Verheyen, T.

In order to develop separation processes and analytical methods for aromatic carboxylic acids for the coal oxidation products, the separation behavior of aromatic carboxylic acids on a reversed-phase HPLC using eluent containing quaternary ammonium salt has been investigated. The retention mechanism of aromatic carboxylic acids was discussed on the basis of both ion-pair partition model and ion-exchange model. The retention behavior of aromatic carboxylic acids possessing one (or two) carboxylic acid group(s) followed the ion-pair partition model, where linear free energy relationship was observed between the capacity factor and the extraction equilibrium constants of benzoic acid and naphthalene carboxylic acid.more » Besides, the retention behavior followed ion-exchange model with increasing the number of carboxylic acids, where the capacity factor of benzene polycarboxylic acids is proportional to the association constants between aromatic acids and quaternary ammonium ions calculated on the basis of an electrostatic interaction model.« less

Organic reactions for the electrochemical and photochemical production of chemical fuels from CO2--The reduction chemistry of carboxylic acids and derivatives as bent CO2 surrogates.

PubMed

Luca, Oana R; Fenwick, Aidan Q

2015-11-01

The present review covers organic transformations involved in the reduction of CO2 to chemical fuels. In particular, we focus on reactions of CO2 with organic molecules to yield carboxylic acid derivatives as a first step in CO2 reduction reaction sequences. These biomimetic initial steps create opportunities for tandem electrochemical/chemical reductions. We draw parallels between long-standing knowledge of CO2 reactivity from organic chemistry, organocatalysis, surface science and electrocatalysis. We point out some possible non-faradaic chemical reactions that may contribute to product distributions in the production of solar fuels from CO2. These reactions may be accelerated by thermal effects such as resistive heating and illumination. Copyright © 2015 Elsevier B.V. All rights reserved.

A Bio-Catalytic Approach to Aliphatic Ketones

PubMed Central

Xiong, Mingyong; Deng, Jin; Woodruff, Adam P.; Zhu, Minshan; Zhou, Jun; Park, Sun Wook; Li, Hui; Fu, Yao; Zhang, Kechun

2012-01-01

Depleting oil reserves and growing environmental concerns have necessitated the development of sustainable processes to fuels and chemicals. Here we have developed a general metabolic platform in E. coli to biosynthesize carboxylic acids. By engineering selectivity of 2-ketoacid decarboxylases and screening for promiscuous aldehyde dehydrogenases, synthetic pathways were constructed to produce both C5 and C6 acids. In particular, the production of isovaleric acid reached 32 g/L (0.22 g/g glucose yield), which is 58% of the theoretical yield. Furthermore, we have developed solid base catalysts to efficiently ketonize the bio-derived carboxylic acids such as isovaleric acid and isocaproic acid into high volume industrial ketones: methyl isobutyl ketone (MIBK, yield 84%), diisobutyl ketone (DIBK, yield 66%) and methyl isoamyl ketone (MIAK, yield 81%). This hybrid “Bio-Catalytic conversion” approach provides a general strategy to manufacture aliphatic ketones, and represents an alternate route to expanding the repertoire of renewable chemicals. PMID:22416247

A bio-catalytic approach to aliphatic ketones.

PubMed

Xiong, Mingyong; Deng, Jin; Woodruff, Adam P; Zhu, Minshan; Zhou, Jun; Park, Sun Wook; Li, Hui; Fu, Yao; Zhang, Kechun

2012-01-01

Depleting oil reserves and growing environmental concerns have necessitated the development of sustainable processes to fuels and chemicals. Here we have developed a general metabolic platform in E. coli to biosynthesize carboxylic acids. By engineering selectivity of 2-ketoacid decarboxylases and screening for promiscuous aldehyde dehydrogenases, synthetic pathways were constructed to produce both C5 and C6 acids. In particular, the production of isovaleric acid reached 32 g/L (0.22 g/g glucose yield), which is 58% of the theoretical yield. Furthermore, we have developed solid base catalysts to efficiently ketonize the bio-derived carboxylic acids such as isovaleric acid and isocaproic acid into high volume industrial ketones: methyl isobutyl ketone (MIBK, yield 84%), diisobutyl ketone (DIBK, yield 66%) and methyl isoamyl ketone (MIAK, yield 81%). This hybrid "Bio-Catalytic conversion" approach provides a general strategy to manufacture aliphatic ketones, and represents an alternate route to expanding the repertoire of renewable chemicals.

Synthesis of carbon-11-labeled 4-(phenylamino)-pyrrolo[2,1-f][1,2,4]triazine derivatives as new potential PET tracers for imaging of p38α mitogen-activated protein kinase.

PubMed

Wang, Min; Gao, Mingzhang; Zheng, Qi-Huang

2014-08-15

The reference standards methyl 4-(2-methyl-5-(methoxycarbamoyl)phenylamino)-5-methylpyrrolo[2,1-f][1,2,4]triazine-6-carboxylate (10a), methyl 4-(2-methyl-5-(ethoxycarbamoyl)phenylamino)-5-methylpyrrolo[2,1-f][1,2,4]triazine-6-carboxylate (10b) and corresponding precursors 4-(2-methyl-5-(methoxycarbamoyl)phenylamino)-5-methylpyrrolo[2,1-f][1,2,4]triazine-6-carboxylic acid (11a), methyl 4-(2-methyl-5-(ethoxycarbamoyl)phenylamino)-5-methylpyrrolo[2,1-f][1,2,4]triazine-6-carboxylic acid (11b) were synthesized from methyl crotonate and 3-amino-4-methylbenzoic acid in multiple steps with moderate to excellent yields. The target tracer [(11)C]methyl 4-(2-methyl-5-(methoxycarbamoyl)phenylamino)-5-methylpyrrolo[2,1-f][1,2,4]triazine-6-carboxylate ([(11)C]10a) and [(11)C]methyl 4-(2-methyl-5-(ethoxycarbamoyl)phenylamino)-5-methylpyrrolo[2,1-f][1,2,4]triazine-6-carboxylate ([(11)C]10b) were prepared from their corresponding precursors with [(11)C]CH3OTf under basic condition through O-[(11)C]methylation and isolated by a simplified solid-phase extraction (SPE) method in 50-60% radiochemical yields at end of bombardment (EOB) with 185-555 GBq/μmol specific activity at end of synthesis (EOS). Copyright © 2014 Elsevier Ltd. All rights reserved.

Chemistry of anti-AIDS and anticancer compounds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, S.

1992-01-01

Several types of prodrugs of 2[prime], 3[prime]-dideoxynucleosides were designed and synthesized for evaluation as anti-AIDS drugs. These prodrugs include 5[prime]-O-acyl-2[prime], 3[prime]-dideoxynucleosides, in which the acyl groups are derived from both aromatic and aliphatic acids, [alpha]-amino acids, diacylglycerol carbonic acids, and diacylglycerol carbamic acids. By applying the pyridium-dihydropyridine redox delivery system to deliver 2[prime], 3[prime]-dideoxynucleosides to the central nervous system, 1,4-dihydropyridine-2[prime], 3[prime]-dideoxy-inosine and -adenosine compounds were synthesized. 5[prime]-Esters of 2[prime], 3[prime]-dideoxyinosine and 2[prime], 3[prime]-dideoxyadenosine were evaluated for their activity against the HIV-1 virus and for delivery to the central nervous system (CNS). The isomerization, hydrolysis, and oxidation of alkyl 1,4-dihydro-N-methylpyridine-3-carboxylates weremore » studied by [sup 1]H and [sup 13]C NMR spectroscopy. Three intermediates, 1,4-dihydro-N-methylpyridine-3-carboxylic acid, alkyl (methyl or isopropyl) 1,6-dihydro-N-methylpyridine-3-carboxylate, and 1,6-dihydro-N-methylpyridine-3-carboxylic acid, were observed by [sup 1]H and [sup 13]C NMR spectroscopy, and their percentages in solution were determined. The structures of the 1,6-dihydropyridine intermediates were confirmed by comparison of the NMR spectra with those of an authentic model compound, methyl N-(4-chlorobenzyl)-1,6-dihydropyridine-3-carboxylate. The rate of hydrolysis of alkyl 1,4-dihydro-N-methylpyridine-3-carboxylates depends on the steric bulk of the O-alkyl group. A new type of 1,4-dihydropyridine drug delivery system with a three-carbon spacer group, 9-[2,3-di-O-acetyl-5-O-[3-(1,4-dihydro-N-methylpyridine-3-carboxamido)propionyl]-[beta]-D-arabinofuranosyl]adenine was designed, synthesized, and evaluated to deliver ara-ADA to the CNS for treatment of herpes encephalitis.« less

Carboxylate-assisted C–H activation of phenylpyridines with copper, palladium and ruthenium: a mass spectrometry and DFT study† †Electronic supplementary information (ESI) available: Details on the mass-spectrometry experiments and theoretical calculations, Hammett studies, potential energy surfaces, energies, optimized Gaussian geometries and laser-power dependence during the IRMPD spectra measurements. See DOI: 10.1039/c5sc01729g

PubMed Central

Gray, A.; Tsybizova, A.

2015-01-01

The C–H activation of 2-phenylpyridine, catalyzed by copper(ii), palladium(ii) and ruthenium(ii) carboxylates, was studied in the gas phase. ESI-MS, infrared multiphoton dissociation spectroscopy and quantum chemical calculations were combined to investigate the intermediate species in the reaction. Collision induced dissociation (CID) experiments and DFT calculations allowed estimation of the energy required for this C–H activation step and the subsequent acetic acid loss. Hammett plots constructed from the CID experiments using different copper carboxylates as catalysts revealed that the use of stronger acids accelerates the C–H activation step. The reasoning can be traced from the associated transition structures that suggest a concerted mechanism and the key effect of the carbon–metal bond pre-formation. Carboxylates derived from stronger acids make the metal atom more electrophilic and therefore shift the reaction towards the formation of C–H activated products. PMID:29861892

Total Acid Value Titration of Hydrotreated Biomass Fast Pyrolysis Oil: Determination of Carboxylic Acids and Phenolics with Multiple End-Point Detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Christensen, E.; Alleman, T. L.; McCormick, R. L.

Total acid value titration has long been used to estimate corrosive potential of petroleum crude oil and fuel oil products. The method commonly used for this measurement, ASTM D664, utilizes KOH in isopropanol as the titrant with potentiometric end point determination by pH sensing electrode and Ag/AgCl reference electrode with LiCl electrolyte. A natural application of the D664 method is titration of pyrolysis-derived bio-oil, which is a candidate for refinery upgrading to produce drop in fuels. Determining the total acid value of pyrolysis derived bio-oil has proven challenging and not necessarily amenable to the methodology employed for petroleum products duemore » to the different nature of acids present. We presented an acid value titration for bio-oil products in our previous publication which also utilizes potentiometry using tetrabutylammonium hydroxide in place of KOH as the titrant and tetraethylammonium bromide in place of LiCl as the reference electrolyte to improve the detection of these types of acids. This method was shown to detect numerous end points in samples of bio-oil that were not detected by D664. These end points were attributed to carboxylic acids and phenolics based on the results of HPLC and GC-MS studies. Additional work has led to refinement of the method and it has been established that both carboxylic acids and phenolics can be determined accurately. Use of pH buffer calibration to determine half-neutralization potentials of acids in conjunction with the analysis of model compounds has allowed us to conclude that this titration method is suitable for the determination of total acid value of pyrolysis oil and can be used to differentiate and quantify weak acid species. The measurement of phenolics in bio-oil is subject to a relatively high limit of detection, which may limit the utility of titrimetric methodology for characterizing the acidic potential of pyrolysis oil and products.« less

Purification Or Organic Acids Using Anion Exchange Chromatography.

DOEpatents

Ponnampalam; Elankovan

2001-09-04

Disclosed is a cost-effective method for purifying and acidifying carboxylic acids, including organic acids and amino acids. The method involves removing impurities by allowing the anionic form of the carboxylic acid to bind to an anion exchange column and washing the column. The carboxylic anion is displaced as carboxylic acid by washing the resin with a strong inorganic anion. This method is effective in removing organic carboxylic acids and amino acids from a variety of industrial sources, including fermentation broths, hydrolysates, and waste streams.

Estimated congener specific gas-phase atmospheric behavior and fractionation of perfluoroalkyl compounds: rates of reaction with atmospheric oxidants, air-water partitioning, and wet/dry deposition lifetimes.

PubMed

Rayne, Sierra; Forest, Kaya; Friesen, Ken J

2009-08-01

A quantitative structure-activity model has been validated for estimating congener specific gas-phase hydroxyl radical reaction rates for perfluoroalkyl sulfonic acids (PFSAs), carboxylic acids (PFCAs), aldehydes (PFAls) and dihydrates, fluorotelomer olefins (FTOls), alcohols (FTOHs), aldehydes (FTAls), and acids (FTAcs), and sulfonamides (SAs), sulfonamidoethanols (SEs), and sulfonamido carboxylic acids (SAAs), and their alkylated derivatives based on calculated semi-empirical PM6 method ionization potentials. Corresponding gas-phase reaction rates with nitrate radicals and ozone have also been estimated using the computationally derived ionization potentials. Henry's law constants for these classes of perfluorinated compounds also appear to be reasonably approximated by the SPARC software program, thereby allowing estimation of wet and dry atmospheric deposition rates. Both congener specific gas-phase atmospheric and air-water interface fractionation of these compounds is expected, complicating current source apportionment perspectives and necessitating integration of such differential partitioning influences into future multimedia models. The findings will allow development and refinement of more accurate and detailed local through global scale atmospheric models for the atmospheric fate of perfluoroalkyl compounds.

An enantioselective approach toward 3,4-dihydroisocoumarin through the bromocyclization of styrene-type carboxylic acids.

PubMed

Chen, Jie; Zhou, Ling; Tan, Chong Kiat; Yeung, Ying-Yeung

2012-01-20

A facile and enantioselective approach toward 3,4-dihydroisocoumarin was developed. The method involved an amino-thiocarbamate catalyzed enantioselective bromocyclization of styrene-type carboxylic acids, yielding 3-bromo-3,4-dihydroisocoumarins with good yields and ee's. 3-Bromo-3,4-dihydroisocoumarins are versatile building blocks for various dihydroisocoumarin derivatives in which the Br group can readily be modified to achieve biologically important 4-O-type and 4-N-type 3,4-dihydroisocoumarin systems. In addition, studies indicated that, by refining some parameters, the synthetically useful 5-exo phthalide products could be achieved with good yields and ee's.

pH at the micellar interface: synthesis of pH probes derived from salicylic acid, acid-base dissociation in sodium dodecyl sulfate micelles, and Poisson-Boltzmann simulation.

PubMed

Souza, T P; Zanette, D; Kawanami, A E; de Rezende, L; Ishiki, H M; do Amaral, A T; Chaimovich, H; Agostinho-Neto, A; Cuccovia, I M

2006-05-01

The study of the H+ concentration at the micellar interface is a convenient system for modeling the distribution of H+ at interfaces. We have synthesized salicylic acid derivatives to analyze the proton dissociation of both the carboxylic and phenol groups of the probes, determining spectrophotometrically the apparent pK(a)'s (pK(ap)) in sodium dodecyl sulfate, SDS, micelles with and without added salt. The synthesized probes were 2-hydroxy-5-(2-trimethylammoniumacetyl)benzoate; 2-hydroxy-5-(2-dimethylhexadecylammoniumacetyl)benzoate; 2-hydroxy-5-(2-dimethylhexadecylammoniumhexanoyl)benzoate; 2-hydroxy-5-(2-dimethylhexadecylammoniumundecanoyl)benzoate; 2-hydroxy-5-acetylbenzoic acid; and 2-hydroxy-5-dodecanoylbenzoic acid. Upon incorporation into SDS micelles the pK(ap)'s of both carboxylic and phenol groups increased by ca. 3 pH units and NaCl addition caused a decrease in the probe-incorporated pK(ap). The experimental results were fitted with a cell model Poisson-Boltzmann (P-B) equation taking in consideration the effect of salt on the aggregation number of SDS and using the distance of the dissociating group as a parameter. The conformations of the probes were analyzed theoretically using two dielectric constants, e.g., 2 and 78. Both the P-B analysis and conformation calculations can be interpreted by assuming that the acid groups dissociate very close to, or at, the interface. Our results are consistent with the assumption that the intrinsic pK(a)'s of both carboxylic and phenol groups of the salicylic acid probes used here can be taken as those in water. Using this assumption the micellar and salt effects on the pK(ap)'s of the (trialkylammonium)benzoate probes were described accurately using a cell model P-B analysis.

Direct hydrogenation of biomass-derived butyric acid to n-butanol over a ruthenium-tin bimetallic catalyst.

PubMed

Lee, Jong-Min; Upare, Pravin P; Chang, Jong-San; Hwang, Young Kyu; Lee, Jeong Ho; Hwang, Dong Won; Hong, Do-Young; Lee, Seung Hwan; Jeong, Myung-Geun; Kim, Young Dok; Kwon, Young-Uk

2014-11-01

Catalytic hydrogenation of organic carboxylic acids and their esters, for example, cellulosic ethanol from fermentation of acetic acid and hydrogenation of ethyl acetate is a promising possibility for future biorefinery concepts. A hybrid conversion process based on selective hydrogenation of butyric acid combined with fermentation of glucose has been developed for producing biobutanol. ZnO-supported Ru-Sn bimetallic catalysts exhibits unprecedentedly superior performance in the vapor-phase hydrogenation of biomass-derived butyric acid to n-butanol (>98% yield) for 3500 h without deactivation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pentafluorophenylammonium triflate (PFPAT) catalyzed facile construction of substituted chromeno[2,3-d]pyrimidinone derivatives and their antimicrobial activity

PubMed Central

Ghashang, Majid; Mansoor, Syed Sheik; Aswin, Krishnamoorthy

2013-01-01

A new, simple thermally efficient and solvent-free condensation of 2-amino-3-cyano-6-methyl-4-phenyl-4H-pyran-5-ethylcarboxylate derivatives with coumarin-3-carboxylic acid employing pentafluorophenylammonium triflate (PFPAT) as an inexpensive organocatalyst for the synthesis of a series of ethyl 4,5-dihydro 7-methyl-2-(2-oxo-2H-chromen-3-yl)-4-oxo-5-aryl-3H-chromeno[2,3-d]pyrimidine-6-carboxylate derivatives is described. This method has the advantages of high yields, a cleaner reaction, simple methodology, short reaction times, easy workup, and greener conditions. All the compounds were evaluated for their in vitro antimicrobial activity against different bacterial and fungal strains. PMID:25685489

Systematic evaluation and optimization of modification reactions of oligonucleotides with amines and carboxylic acids for the synthesis of DNA-encoded chemical libraries.

PubMed

Franzini, Raphael M; Samain, Florent; Abd Elrahman, Maaly; Mikutis, Gediminas; Nauer, Angela; Zimmermann, Mauro; Scheuermann, Jörg; Hall, Jonathan; Neri, Dario

2014-08-20

DNA-encoded chemical libraries are collections of small molecules, attached to DNA fragments serving as identification barcodes, which can be screened against multiple protein targets, thus facilitating the drug discovery process. The preparation of large DNA-encoded chemical libraries crucially depends on the availability of robust synthetic methods, which enable the efficient conjugation to oligonucleotides of structurally diverse building blocks, sharing a common reactive group. Reactions of DNA derivatives with amines and/or carboxylic acids are particularly attractive for the synthesis of encoded libraries, in view of the very large number of building blocks that are commercially available. However, systematic studies on these reactions in the presence of DNA have not been reported so far. We first investigated conditions for the coupling of primary amines to oligonucleotides, using either a nucleophilic attack on chloroacetamide derivatives or a reductive amination on aldehyde-modified DNA. While both methods could be used for the production of secondary amines, the reductive amination approach was generally associated with higher yields and better purity. In a second endeavor, we optimized conditions for the coupling of a diverse set of 501 carboxylic acids to DNA derivatives, carrying primary and secondary amine functions. The coupling efficiency was generally higher for primary amines, compared to secondary amine substituents, but varied considerably depending on the structure of the acids and on the synthetic methods used. Optimal reaction conditions could be found for certain sets of compounds (with conversions >80%), but multiple reaction schemes are needed when assembling large libraries with highly diverse building blocks. The reactions and experimental conditions presented in this article should facilitate the synthesis of future DNA-encoded chemical libraries, while outlining the synthetic challenges that remain to be overcome.

Novel Three-Component Phenazine-1-Carboxylic Acid 1,2-Dioxygenase in Sphingomonas wittichii DP58

PubMed Central

Zhao, Qiang; Wang, Wei; Huang, Xian-Qing; Zhang, Xue-Hong

2017-01-01

ABSTRACT Phenazine-1-carboxylic acid, the main component of shenqinmycin, is widely used in southern China for the prevention of rice sheath blight. However, the fate of phenazine-1-carboxylic acid in soil remains uncertain. Sphingomonas wittichii DP58 can use phenazine-1-carboxylic acid as its sole carbon and nitrogen sources for growth. In this study, dioxygenase-encoding genes, pcaA1A2, were found using transcriptome analysis to be highly upregulated upon phenazine-1-carboxylic acid biodegradation. PcaA1 shares 68% amino acid sequence identity with the large oxygenase subunit of anthranilate 1,2-dioxygenase from Rhodococcus maanshanensis DSM 44675. The dioxygenase was coexpressed in Escherichia coli with its adjacent reductase-encoding gene, pcaA3, and ferredoxin-encoding gene, pcaA4, and showed phenazine-1-carboxylic acid consumption. The dioxygenase-, ferredoxin-, and reductase-encoding genes were expressed in Pseudomonas putida KT2440 or E. coli BL21, and the three recombinant proteins were purified. A phenazine-1-carboxylic acid conversion capability occurred in vitro only when all three components were present. However, P. putida KT2440 transformed with pcaA1A2 obtained phenazine-1-carboxylic acid degradation ability, suggesting that phenazine-1-carboxylic acid 1,2-dioxygenase has low specificities for its ferredoxin and reductase. This was verified by replacing PcaA3 with RedA2 in the in vitro enzyme assay. High-performance liquid chromatography–mass spectrometry (HPLC-MS) and nuclear magnetic resonance (NMR) analysis showed that phenazine-1-carboxylic acid was converted to 1,2-dihydroxyphenazine through decarboxylation and hydroxylation, indicating that PcaA1A2A3A4 constitutes the initial phenazine-1-carboxylic acid 1,2-dioxygenase. This study fills a gap in our understanding of the biodegradation of phenazine-1-carboxylic acid and illustrates a new dioxygenase for decarboxylation. IMPORTANCE Phenazine-1-carboxylic acid is widely used in southern China as a key fungicide to prevent rice sheath blight. However, the degradation characteristics of phenazine-1-carboxylic acid and the environmental consequences of the long-term application are not clear. S. wittichii DP58 can use phenazine-1-carboxylic acid as its sole carbon and nitrogen sources. In this study, a three-component dioxygenase, PcaA1A2A3A4, was determined to be the initial dioxygenase for phenazine-1-carboxylic acid degradation in S. wittichii DP58. Phenazine-1-carboxylic acid was converted to 1,2-dihydroxyphenazine through decarboxylation and hydroxylation. This finding may help us discover the pathway for phenazine-1-carboxylic acid degradation. PMID:28188209

Chelating Tendencies of Bioactive Aminophosphonates

PubMed Central

Lázár, István; Kafarski, Pawel

1994-01-01

The metal-binding abilities of a wide variety of bioactive aminophosphonates, from the simple aminoethanephosphonic acids to the rather large macrocyclic polyaza derivatives, are discussed with special emphasis on a comparison of the analogous carboxylic acid and phosphonic acid systems. Examples are given of the biological importance of metal ion – aminophosphonate interactions in living systems, and also of their actual and potential applicability in medicine. PMID:18476237

Process for producing peracids from aliphatic hydroxy carboxylic acids

DOEpatents

Chum, Helena L.; Ratcliff, Matthew A.; Palasz, Peter D.

1986-01-01

A process for producing peracids from lactic acid-containing solutions derived from biomass processing systems comprising: adjusting the pH of the solution to about 8-9 and removing alkaline residue fractions therefrom to form a solution comprised substantially of lower aliphatic hydroxy acids; oxidizing the solution to produce volatile lower aliphatic aldehydes; removing said aldehydes as they are generated; and converting said aldehydes to peracids.

Biopolymers as an Alternative to Petroleum-Based Polymers for Soil Modification; ESTCP ER-0920: Treatability Studies

DTIC Science & Technology

2012-08-01

carboxylic, amine, hydroxyl). Molasses produced more carboxylic acid groups than the corn syrup -based material and was composed of high ...molecular weight EPS units (as high as 800 KDa). Corn syrup -derived biopolymer, on the other hand, showed a greater number of small molecular weight...biopolymer by R. tropici: corn syrup , maltose, sorghum, and molasses. The maltose, being a very expensive carbon source, has been replaced by the sorghum

Biopolymers as an Alternative to Petroleum-Based Polymers for Soil Modification, ESTCP ER-0920: Treatability Studies

DTIC Science & Technology

2012-08-01

carboxylic, amine, hydroxyl). Molasses produced more carboxylic acid groups than the corn syrup -based material and was composed of high ...molecular weight EPS units (as high as 800 KDa). Corn syrup -derived biopolymer, on the other hand, showed a greater number of small molecular weight...biopolymer by R. tropici: corn syrup , maltose, sorghum, and molasses. The maltose, being a very expensive carbon source, has been replaced by the sorghum

Regeneration of carboxylic acid-laden basic sorbents by leaching with a volatile base in an organic solvent

DOEpatents

King, C. Judson; Husson, Scott M.

1999-01-01

Carboxylic acids are sorbed from aqueous feedstocks onto a solid adsorbent. The acids are freed from the sorbent phase by treating it with an organic solution of alkylamine thus forming an alkylamine/carboxylic acid complex which is decomposed with improved efficiency to the desired carboxylic acid and the alkylamine. Carbon dioxide addition can be used to improve the adsorption or the carboxylic acids by the solid phase sorbent.

Exploring sequence requirements for C₃/C₄ carboxylate recognition in the Pseudomonas aeruginosa cephalosporinase: Insights into plasticity of the AmpC β-lactamase.

PubMed

Drawz, Sarah M; Taracila, Magdalena; Caselli, Emilia; Prati, Fabio; Bonomo, Robert A

2011-06-01

In Pseudomonas aeruginosa, the chromosomally encoded class C cephalosporinase (AmpC β-lactamase) is often responsible for high-level resistance to β-lactam antibiotics. Despite years of study of these important β-lactamases, knowledge regarding how amino acid sequence dictates function of the AmpC Pseudomonas-derived cephalosporinase (PDC) remains scarce. Insights into structure-function relationships are crucial to the design of both β-lactams and high-affinity inhibitors. In order to understand how PDC recognizes the C₃/C₄ carboxylate of β-lactams, we first examined a molecular model of a P. aeruginosa AmpC β-lactamase, PDC-3, in complex with a boronate inhibitor that possesses a side chain that mimics the thiazolidine/dihydrothiazine ring and the C₃/C₄ carboxylate characteristic of β-lactam substrates. We next tested the hypothesis generated by our model, i.e. that more than one amino acid residue is involved in recognition of the C₃/C₄ β-lactam carboxylate, and engineered alanine variants at three putative carboxylate binding amino acids. Antimicrobial susceptibility testing showed that the PDC-3 β-lactamase maintains a high level of activity despite the substitution of C₃/C₄ β-lactam carboxylate recognition residues. Enzyme kinetics were determined for a panel of nine penicillin and cephalosporin analog boronates synthesized as active site probes of the PDC-3 enzyme and the Arg349Ala variant. Our examination of the PDC-3 active site revealed that more than one residue could serve to interact with the C₃/C₄ carboxylate of the β-lactam. This functional versatility has implications for novel drug design, protein evolution, and resistance profile of this enzyme. Copyright © 2011 The Protein Society.

Alkali-catalyzed low temperature wet crosslinking of plant proteins using carboxylic acids.

PubMed

Reddy, Narendra; Li, Ying; Yang, Yiqi

2009-01-01

We report the development of a new method of alkali-catalyzed low temperature wet crosslinking of plant proteins to improve their breaking tenacity without using high temperatures or phosphorus-containing catalysts used in conventional poly(carboxylic acid) crosslinking of cellulose and proteins. Carboxylic acids are preferred over aldehyde-containing crosslinkers for crosslinking proteins and cellulose because of their low toxicity and cost and ability to improve the desired properties of the materials. However, current knowledge in carboxylic acid crosslinking of proteins and cellulose requires the use of carboxylic acids with at least three carboxylic groups, toxic phosphorous-containing catalysts and curing at high temperatures (150-185 degrees C). The use of high temperatures and low pH in conventional carboxylic acid crosslinking has been reported to cause substantial strength loss and/or undesired changes in the properties of the crosslinked materials. In this research, gliadin, soy protein, and zein fibers have been crosslinked with malic acid, citric acid, and butanetetracarboxylic acid to improve the tenacity of the fibers without using high temperatures and phosphorus-containing catalysts. The new method of wet crosslinking using carboxylic acids containing two or more carboxylic groups will be useful to crosslink proteins for various industrial applications.

Structural and stereoelectronic insights into oxygenase-catalyzed formation of ethylene from 2-oxoglutarate.

PubMed

Zhang, Zhihong; Smart, Tristan J; Choi, Hwanho; Hardy, Florence; Lohans, Christopher T; Abboud, Martine I; Richardson, Melodie S W; Paton, Robert S; McDonough, Michael A; Schofield, Christopher J

2017-05-02

Ethylene is important in industry and biological signaling. In plants, ethylene is produced by oxidation of 1-aminocyclopropane-1-carboxylic acid, as catalyzed by 1-aminocyclopropane-1-carboxylic acid oxidase. Bacteria catalyze ethylene production, but via the four-electron oxidation of 2-oxoglutarate to give ethylene in an arginine-dependent reaction. Crystallographic and biochemical studies on the Pseudomonas syringae ethylene-forming enzyme reveal a branched mechanism. In one branch, an apparently typical 2-oxoglutarate oxygenase reaction to give succinate, carbon dioxide, and sometimes pyrroline-5-carboxylate occurs. Alternatively, Grob-type oxidative fragmentation of a 2-oxoglutarate-derived intermediate occurs to give ethylene and carbon dioxide. Crystallographic and quantum chemical studies reveal that fragmentation to give ethylene is promoted by binding of l-arginine in a nonoxidized conformation and of 2-oxoglutarate in an unprecedented high-energy conformation that favors ethylene, relative to succinate formation.

Secondary Structures in a Freeze-Dried Lignite Humic Acid Fraction Caused by Hydrogen-Bonding of Acidic Protons with Aromatic Rings.

PubMed

Cao, Xiaoyan; Drosos, Marios; Leenheer, Jerry A; Mao, Jingdong

2016-02-16

A lignite humic acid (HA) was separated from inorganic and non-HA impurities (i.e., aluminosilicates, metals) and fractionated by a combination of dialysis and XAD-8 resin. Fractionation revealed a more homogeneous structure of lignite HA. New and more specific structural information on the main lignite HA fraction is obtained by solid-state nuclear magnetic resonance (NMR) spectroscopy. Quantitative (13)C multiple cross-polarization (multiCP) NMR indicated oxidized phenyl propane structures derived from lignin. MultiCP experiments, conducted on potassium HA salts titrated to pH 10 and pH 12, revealed shifts consistent with carboxylate and phenolate formation, but structural changes associated with enolate formation from aromatic beta keto acids were not detected. Two-dimensional (1)H-(13)C heteronuclear correlation (2D HETCOR) NMR indicated aryl-aliphatic ketones, aliphatic and aromatic carboxyl groups, phenol, and methoxy phenyl ethers. Acidic protons from carboxyl groups in both the lignite HA fraction and a synthetic HA-like polycondensate were found to be hydrogen-bonded with electron-rich aromatic rings. Our results coupled with published infrared spectra provide evidence for the preferential hydrogen bonding of acidic hydrogens with electron-rich aromatic rings rather than adjacent carbonyl groups. These hydrogen-bonding interactions likely result from stereochemical arrangements in primary structures and folding.

16 CFR 303.7 - Generic names and definitions for manufactured fibers.

Code of Federal Regulations, 2011 CFR

2011-01-01

... least 85% by weight of lactic acid ester units derived from naturally occurring sugars. (Sec. 6, 72 Stat... composed of at least 85% by weight of an ester of a substituted aromatic carboxylic acid, including but not... description of the fiber. (d) Rayon.A manufactured fiber composed of regenerated cellulose, as well as...

16 CFR 303.7 - Generic names and definitions for manufactured fibers.

Code of Federal Regulations, 2014 CFR

2014-01-01

... least 85% by weight of lactic acid ester units derived from naturally occurring sugars. (Sec. 6, 72 Stat... composed of at least 85% by weight of an ester of a substituted aromatic carboxylic acid, including but not... description of the fiber. (d) Rayon.A manufactured fiber composed of regenerated cellulose, as well as...

16 CFR 303.7 - Generic names and definitions for manufactured fibers.

Code of Federal Regulations, 2012 CFR

2012-01-01

... least 85% by weight of lactic acid ester units derived from naturally occurring sugars. (Sec. 6, 72 Stat... composed of at least 85% by weight of an ester of a substituted aromatic carboxylic acid, including but not... description of the fiber. (d) Rayon.A manufactured fiber composed of regenerated cellulose, as well as...

16 CFR 303.7 - Generic names and definitions for manufactured fibers.

Code of Federal Regulations, 2010 CFR

2010-01-01

... least 85% by weight of lactic acid ester units derived from naturally occurring sugars. (Sec. 6, 72 Stat... composed of at least 85% by weight of an ester of a substituted aromatic carboxylic acid, including but not... description of the fiber. (d) Rayon—A manufactured fiber composed of regenerated cellulose, as well as...

16 CFR 303.7 - Generic names and definitions for manufactured fibers.

Code of Federal Regulations, 2013 CFR

2013-01-01

... least 85% by weight of lactic acid ester units derived from naturally occurring sugars. (Sec. 6, 72 Stat... composed of at least 85% by weight of an ester of a substituted aromatic carboxylic acid, including but not... description of the fiber. (d) Rayon.A manufactured fiber composed of regenerated cellulose, as well as...

Porous structure and surface chemistry of phosphoric acid activated carbon from corncob

NASA Astrophysics Data System (ADS)

Sych, N. V.; Trofymenko, S. I.; Poddubnaya, O. I.; Tsyba, M. M.; Sapsay, V. I.; Klymchuk, D. O.; Puziy, A. M.

2012-11-01

Active carbons have been prepared from corncob using chemical activation with phosphoric acid at 400 °C using varied ratio of impregnation (RI). Porous structure of carbons was characterized by nitrogen adsorption and scanning electron microscopy. Surface chemistry was studied by IR and potentiometric titration method. It has been shown that porosity development was peaked at RI = 1.0 (SBET = 2081 m2/g, Vtot = 1.1 cm3/g), while maximum amount of acid surface groups was observed at RI = 1.25. Acid surface groups of phosphoric acid activated carbons from corncob includes phosphate and strongly acidic carboxylic (pK = 2.0-2.6), weakly acidic carboxylic (pK = 4.7-5.0), enol/lactone (pK = 6.7-7.4; 8.8-9.4) and phenol (pK = 10.1-10.7). Corncob derived carbons showed high adsorption capacity to copper, especially at low pH. Maximum adsorption of methylene blue and iodine was observed for carbon with most developed porosity (RI = 1.0).

Nanoconfinement Effects in Catalysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kung, Harold H.

In this investigation, the unique properties that stem from the constrained environment and enforced proximity of functional groups at the active site were demonstrated for a number of systems. The first system is a nanocage structure with silicon-based, atom-thick shells and molecular-size cavities. The shell imparts the expected size exclusion for access to the interior cavity, and the confined space together with the hydrophobic shell strongly influences the stability of charged groups. One consequence is that the interior amine groups in a siloxane nanocage exhibit a shift in their protonation ability that is equivalent to about 4 pH units. Inmore » another nanocage structure designed to possess a core-shell structure in which the core periphery is decorated with carboxylic acid groups and the shell interior is populated with silanol groups, the restricted motion of the core results in limiting the stoichiometry of reaction between carboxylic acid and a Co 2CO 8 complex, which leads to formation and stabilization of Co(I) ions in the nanocage. The second designed catalytic structure is a supported, isolated, Lewis acid Sn-oxide unit derived from a (POSS)-Sn-(POSS) molecular complex (POSS = incompletely condensed silsesquioxane). The Sn center in the (POSS)-Sn-(POSS) complex is present in a tetrahedral coordination, as confirmed by single crystal x-ray crystallography and Sn NMR, and its Lewis acid character is demonstrated with its binding to amines. The retention of the tetrahedral coordination of Sn after heterogenization and mild oxidative treatment is confirmed by characterization using EXAFS, NMR, UV-vis, and DRIFT, and its Lewis acid character is confirmed by stoichiometric binding with pyridine. This Sn-catalyst is active in hydride transfer reactions as a typical solid Lewis acid. In addition, the Sn centers can also create Brønsted acidity with alcohol by binding the alcohol strongly as alkoxide and transferring the hydroxyl H to the neighboring Sn-O-Si bond. The resulting acidic silanol is active in epoxide ring opening and acetalization reactions. The open structure of the Sn center makes it accessible to larger molecules, including cellobiose which can be converted to 5-(hydroxymethyl)-furfural. The third structure is a support planted with functional group pairing of a known separation distance. Using a precursor molecule that contains a hydrolysable silyl ester bond, and making use of known chemistry to convert silanol groups into amino/pyridyl and phosphinyl groups, silica surfaces with carboxylic acid/silanol, carboxylic acid/amine, carboxylic acid/pyridine, and carboxylic acid/phosphine pairs can be constructed. The amino groups paired with carboxylic acid on such a surface is more active in the Henry reaction of 4-nitobenzaldehyde with nitromethane.« less

Design, synthesis, molecular docking, anti-Proteus mirabilis and urease inhibition of new fluoroquinolone carboxylic acid derivatives.

PubMed

Abdullah, Mohammed A A; Abuo-Rahma, Gamal El-Din A A; Abdelhafez, El-Shimaa M N; Hassan, Heba A; Abd El-Baky, Rehab M

2017-02-01

New hydroxamic acid, hydrazide and amide derivatives of ciprofloxacin in addition to their analogues of levofloxacin were prepared and identified by different spectroscopic techniques. Some of the prepared compounds revealed good activity against the urease splitting bacteria, Proteus mirabilis. The urease inhibitory activity was investigated using indophenol method. Most of the tested compounds showed better activity than the reference acetohydroxamic acid (AHA). The ciprofloxacin hydrazide derivative 3a and levofloxacin hydroxamic acid 7 experienced the highest activity (IC 50 =1.22μM and 2.20μM, respectively). Molecular docking study revealed high spontaneous binding ability of the tested compounds to the active site of urease. Copyright © 2016 Elsevier Inc. All rights reserved.

Carboxylic acid sorption regeneration process

DOEpatents

King, C. Judson; Poole, Loree J.

1995-01-01

Carboxylic acids are sorbed from aqueous feedstocks into an organic liquid phase or onto a solid adsorbent. The acids are freed from the sorbent phase by treating it with aqueous alkylamine thus forming an alkylammonium carboxylate which is dewatered and decomposed to the desired carboxylic acid and the alkylamine.

40 CFR 721.2950 - Carboxylic acid glycidyl esters.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Carboxylic acid glycidyl esters. 721... Substances § 721.2950 Carboxylic acid glycidyl esters. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified generically as carboxylic acid glycidyl ester...

Synthesis and characterization of a material derived from 4-mercaptobenzoic acid: A novel platform for oligonucleotide immobilization.

PubMed

Alves, Rafael da Fonseca; da Silva, Amanda Gonçalves; Ferreira, Lucas Franco; Franco, Diego Leoni

2017-04-01

This paper reports the electrochemical modification of pencil carbon graphite electrodes with a polymeric material derived from 4-mercaptobenzoic acid. Acidic solutions (pH 0 and 5.02) yielded an insulating polymeric film with anionic permselective properties. Scanning Electron Microscopy (SEM) analysis showed a complete coverage of the carbon graphite electrodes with a laminar-like polymeric structure. Different characterization studies indicate that the carboxyl group remained unchanged since the absorbance peak and oxidation potential did not change with the increase in pH at the pK a accounting for the carboxyl/carboxylate redox transition. The functionalized matrix was activated using carbodiimide, succinimide and an amine-modified oligonucleotide. The immobilization and hybridization processes were successfully verified using the redox electroactive indicator methylene blue, where better electrochemical signals were obtained when compared with the traditional self-assembled monolayer system. The selectivity of the system was verified using a noncomplementary target where no significant difference in electric current was observed when compared to the system containing only the probe. The method showed a good linear correlation coefficient (r 2 =0.9915), low limit of detection (1.17nmolL -1 ), and an acceptable precision (RSD=2.75%). The proposed method is suitable for further studies using different sequences of oligonucleotides. Copyright © 2016 Elsevier B.V. All rights reserved.

Immune Modulation in Normal Human Peripheral Blood Mononuclear Cells (PBMCs) (Lymphocytes) in Response to Benzofuran-2-Carboxylic Acid Derivative KMEG during Spaceflight

NASA Astrophysics Data System (ADS)

Okoro, Elvis; Mann, Vivek; Ellis, Ivory; Mansoor, Elvedina; Olamigoke, Loretta; Marriott, Karla Sue; Denkins, Pamela; Williams, Willie; Sundaresan, Alamelu

2017-08-01

Microgravity and radiation exposure during space flight have been widely reported to induce the suppression of normal immune system function, and increase the risk of cancer development in humans. These findings pose a serious risk to manned space missions. Interestingly, recent studies have shown that benzofuran-2-carboxylic acid derivatives can inhibit the progression of some of these devastating effects on earth and in modeled microgravity. However, these studies had not assessed the impacts of benzofuran-2- carboxylic acid and its derivatives on global gene expression under spaceflight conditions. In this study, the ability of a specific benzofuran-2-carboxylic acid derivative (KMEG) to confer protection from radiation and restore normal immune function was investigated following exposure to space flight conditions on the ISS. Normal human peripheral blood mononuclear cells (lymphocytes) treated with 10 µ g/ml of KMEG together with untreated control samples were flown on Nanoracks hardware on Spacex-3 flight. The Samples were returned one month later and gene expression was analyzed. A 1g-ground control experiment was performed in parallel at the Kennedy spaceflight center. The first overall subtractive unrestricted analysis revealed 78 genes, which were differentially expressed in space flight KMEG, untreated lymphocytes as compared to the corresponding ground controls. However, in KMEG-treated space flight lymphocytes, there was an increased expression of a group of genes that mediate increased transcription, translation and innate immune system mediating functions of lymphocytes as compared to KMEG-untreated samples. Analysis of genes related to T cell proliferation in spaceflight KMEG-treated lymphocytes compared to 1g-ground KMEG- treated lymphocytes revealed six T cell proliferation and signaling genes to be significantly upregulated (p < 0.001) and five related genes were found to be significantly down-regulated. These genes play a significant role in promoting the proliferation of T-lymphocytes, the regulation of membrane trafficking, promote early response, mediating C-myc related proliferation, promote antiapoptotic activity and protects mitochondria from the accumulation of oxidatively damaged membrane proteins. Overall, our analysis indicates that KMEG promotes T- cell proliferation and has an anti-inflammatory effect, thereby increasing immunity and possible protection from chronic inflammation setting which is optimally required during long term space flights.

Carboxylic acid sorption regeneration process

DOEpatents

King, C.J.; Poole, L.J.

1995-05-02

Carboxylic acids are sorbed from aqueous feedstocks into an organic liquid phase or onto a solid adsorbent. The acids are freed from the sorbent phase by treating it with aqueous alkylamine thus forming an alkylammonium carboxylate which is dewatered and decomposed to the desired carboxylic acid and the alkylamine. 10 figs.

Production of carboxylic acid and salt co-products

DOEpatents

Hanchar, Robert J.; Kleff, Susanne; Guettler, Michael V.

2014-09-09

This invention provide processes for producing carboxylic acid product, along with useful salts. The carboxylic acid product that is produced according to this invention is preferably a C.sub.2-C.sub.12 carboxylic acid. Among the salts produced in the process of the invention are ammonium salts.

Benzothiophene Carboxylate Derivatives as Novel Allosteric Inhibitors of Branched-chain α-Ketoacid Dehydrogenase Kinase*

PubMed Central

Tso, Shih-Chia; Gui, Wen-Jun; Wu, Cheng-Yang; Chuang, Jacinta L.; Qi, Xiangbing; Skvorak, Kristen J.; Dorko, Kenneth; Wallace, Amy L.; Morlock, Lorraine K.; Lee, Brendan H.; Hutson, Susan M.; Strom, Stephen C.; Williams, Noelle S.; Tambar, Uttam K.; Wynn, R. Max; Chuang, David T.

2014-01-01

The mitochondrial branched-chain α-ketoacid dehydrogenase complex (BCKDC) is negatively regulated by reversible phosphorylation. BCKDC kinase (BDK) inhibitors that augment BCKDC flux have been shown to reduce branched-chain amino acid (BCAA) concentrations in vivo. In the present study, we employed high-throughput screens to identify compound 3,6-dichlorobenzo[b]thiophene-2-carboxylic acid (BT2) as a novel BDK inhibitor (IC50 = 3.19 μm). BT2 binds to the same site in BDK as other known allosteric BDK inhibitors, including (S)-α-cholorophenylproprionate ((S)-CPP). BT2 binding to BDK triggers helix movements in the N-terminal domain, resulting in the dissociation of BDK from the BCKDC accompanied by accelerated degradation of the released kinase in vivo. BT2 shows excellent pharmacokinetics (terminal T½ = 730 min) and metabolic stability (no degradation in 240 min), which are significantly better than those of (S)-CPP. BT2, its analog 3-chloro-6-fluorobenzo[b]thiophene-2-carboxylic acid (BT2F), and a prodrug of BT2 (i.e. N-(4-acetamido-1,2,5-oxadiazol-3-yl)-3,6-dichlorobenzo[b]thiophene-2-carboxamide (BT3)) significantly increase residual BCKDC activity in cultured cells and primary hepatocytes from patients and a mouse model of maple syrup urine disease. Administration of BT2 at 20 mg/kg/day to wild-type mice for 1 week leads to nearly complete dephosphorylation and maximal activation of BCKDC in heart, muscle, kidneys, and liver with reduction in plasma BCAA concentrations. The availability of benzothiophene carboxylate derivatives as stable BDK inhibitors may prove useful for the treatment of metabolic disease caused by elevated BCAA concentrations. PMID:24895126

Aldehydes in hydrothermal solution - Standard partial molal thermodynamic properties and relative stabilities at high temperatures and pressures

NASA Technical Reports Server (NTRS)

Schulte, Mitchell D.; Shock, Everett L.

1993-01-01

Aldehydes are common in a variety of geologic environments and are derived from a number of sources, both natural and anthropogenic. Experimental data for aqueous aldehydes were taken from the literature and used, along with parameters for the revised Helgeson-Kirkham-Flowers (HKF) equations of state, to estimate standard partial molal thermodynamic data for aqueous straight-chain alkyl aldehydes at high temperatures and pressures. Examples of calculations involving aldehydes in geological environments are given, and the stability of aldehydes relative to carboxylic acids is evaluated. These calculations indicate that aldehydes may be intermediates in the formation of carboxylic acids from hydrocarbons in sedimentary basin brines and hydrothermal systems like they are in the atmosphere. The data and parameters summarized here allow evaluation of the role of aldehydes in the formation of prebiotic precursors, such as amino acids and hydroxy acids on the early Earth and in carbonaceous chondrite parent bodies.

Cellular uptake and anticancer activity of carboxylated gallium corroles.

PubMed

Pribisko, Melanie; Palmer, Joshua; Grubbs, Robert H; Gray, Harry B; Termini, John; Lim, Punnajit

2016-04-19

We report derivatives of gallium(III) tris(pentafluorophenyl)corrole, 1 [Ga(tpfc)], with either sulfonic (2) or carboxylic acids (3, 4) as macrocyclic ring substituents: the aminocaproate derivative, 3 [Ga(ACtpfc)], demonstrated high cytotoxic activity against all NCI60 cell lines derived from nine tumor types and confirmed very high toxicity against melanoma cells, specifically the LOX IMVI and SK-MEL-28 cell lines. The toxicities of 1, 2, 3, and 4 [Ga(3-ctpfc)] toward prostate (DU-145), melanoma (SK-MEL-28), breast (MDA-MB-231), and ovarian (OVCAR-3) cancer cells revealed a dependence on the ring substituent: IC50values ranged from 4.8 to >200 µM; and they correlated with the rates of uptake, extent of intracellular accumulation, and lipophilicity. Carboxylated corroles 3 and 4, which exhibited about 10-fold lower IC50values (<20 µM) relative to previous analogs against all four cancer cell lines, displayed high efficacy (Emax= 0). Confocal fluorescence imaging revealed facile uptake of functionalized gallium corroles by all human cancer cells that followed the order: 4 > 3 > 2 > 1 (intracellular accumulation of gallium corroles was fastest in melanoma cells). We conclude that carboxylated gallium corroles are promising chemotherapeutics with the advantage that they also can be used for tumor imaging.

Cellular uptake and anticancer activity of carboxylated gallium corroles

PubMed Central

Pribisko, Melanie; Palmer, Joshua; Grubbs, Robert H.; Gray, Harry B.; Termini, John; Lim, Punnajit

2016-01-01

We report derivatives of gallium(III) tris(pentafluorophenyl)corrole, 1 [Ga(tpfc)], with either sulfonic (2) or carboxylic acids (3, 4) as macrocyclic ring substituents: the aminocaproate derivative, 3 [Ga(ACtpfc)], demonstrated high cytotoxic activity against all NCI60 cell lines derived from nine tumor types and confirmed very high toxicity against melanoma cells, specifically the LOX IMVI and SK-MEL-28 cell lines. The toxicities of 1, 2, 3, and 4 [Ga(3-ctpfc)] toward prostate (DU-145), melanoma (SK-MEL-28), breast (MDA-MB-231), and ovarian (OVCAR-3) cancer cells revealed a dependence on the ring substituent: IC50 values ranged from 4.8 to >200 µM; and they correlated with the rates of uptake, extent of intracellular accumulation, and lipophilicity. Carboxylated corroles 3 and 4, which exhibited about 10-fold lower IC50 values (<20 µM) relative to previous analogs against all four cancer cell lines, displayed high efficacy (Emax = 0). Confocal fluorescence imaging revealed facile uptake of functionalized gallium corroles by all human cancer cells that followed the order: 4 >> 3 > 2 >> 1 (intracellular accumulation of gallium corroles was fastest in melanoma cells). We conclude that carboxylated gallium corroles are promising chemotherapeutics with the advantage that they also can be used for tumor imaging. PMID:27044076

Lipase catalyzed epoxidation of fatty acid methyl esters derived from unsaturated vegetable oils in absence of carboxylic acid.

PubMed

Sustaita-Rodríguez, Alejandro; Ramos-Sánchez, Víctor H; Camacho-Dávila, Alejandro A; Zaragoza-Galán, Gerardo; Espinoza-Hicks, José C; Chávez-Flores, David

2018-04-11

Nowadays the industrial chemistry reactions rely on green technologies. Enzymes as lipases are increasing its use in diverse chemical processes. Epoxidized fatty acid methyl esters obtained from transesterification of vegetable oils have recently found applications as polymer plasticizer, agrochemical, cosmetics, pharmaceuticals and food additives. In this research article, grapeseed, avocado and olive oils naturally containing high percents of mono and poly unsaturations were used as starting materials for the production of unsaturated fatty acid methyl esters. The effect of lauric acid as an active oxygen carrier was studied on epoxidation reactions where unsaturated fatty acid methyl esters were converted to epoxy fatty acid methyl esters using immobilized Candida antarctica Lipase type B as catalyst and hydrogen peroxide as oxygen donor at mild temperature and pressure conditions. After this study it was confirmed by 1 H NMR, 13 C NMR and GC-MS that the addition of lauric acid to the enzymatic reaction is unnecessary to transform the alkenes in to epoxides. It was found that quantitative conversions were possible in despite of a carboxylic acid absence.

Theoretical Study of the Thermal Decomposition of Carboxylic Acids at Pyrolysis Temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clark, J. M.; Robichaud, D. J.; Nimlos, M. R.

2013-01-01

Carboxylic acids are important in the processing of biomass into renewable fuels and chemicals. They are formed from the pretreatment and pyrolysis of hemicellulose biopolymers and are released from the decomposition of sugars. They result from the deconstruction of polyhydroxyalkanoates (bacterial carbon storage polymers) from fatty acids derived from algae, bacteria, and oil crops. The thermal deoxygenation of carboxylic acids is an important step in the conversion of biomass into aliphatic hydrocarbons suitable for use in renewable biofuels and as petrochemical replacements. Decarboxylation, a primary decomposition pathway under pyrolysis conditions, represents an ideal conversion process, because it eliminates two atomsmore » of oxygen for every carbon atom removed. Problematically, additional deoxygenation processes exist (e.g. dehydration) that are in direct competition with decarboxylation and result in the formation of reactive and more fragmented end products. To better understand the competition between decarboxylation and other deoxygenation processes and to gain insight into possible catalysts that would favor decarboxylation, we have investigated the mechanisms and thermochemistry of the various unimolecular and bimolecular deoxygenation pathways for a family of C1-C4 organic acids using electronic structure calculations at the M06-2X/6-311++G(2df,p) level of theory.« less

Application of 1-aminocyclohexane carboxylic acid to protein nanostructure computer design

PubMed Central

Rodríguez-Ropero, Francisco; Zanuy, David; Casanovas, Jordi; Nussinov, Ruth; Alemán, Carlos

2009-01-01

Conformationally restricted amino acids are promising candidates to serve as basic pieces in redesigned protein motifs which constitute the basic modules in synthetic nanoconstructs. Here we study the ability of constrained cyclic amino acid 1-aminocyclohexane-1-carboxylic acid (Ac6c) to stabilize highly regular β-helical motifs excised from naturally occurring proteins. Calculations indicate that the conformational flexibility observed in both the ring and the main chain is significantly higher than that detected for other 1-aminocycloalkane-1-carboxylic acid (Acnc, where n refers to the size of the ring) with smaller cycles. Incorporation of Ac6c into the flexible loops of β-helical motifs indicates that the stability of such excised building blocks as well as the nano-assemblies derived from them is significantly enhanced. Thus, the intrinsic Ac6c tendency to adopt folded conformations combined with the low structural strain of the cyclohexane ring confers the ability to both self-adapt to the β-helix motif and to stabilize the overall structure by absorbing part of its conformational fluctuations. Comparison with other Acnc residues indicates that the ability to adapt to the targeted position improves considerably with the ring size, i.e. when the rigidity introduced by the strain of the ring decreases. PMID:18201062

Discovery of a novel acyl-CoA: cholesterol acyltransferase inhibitor: the synthesis, biological evaluation, and reduced adrenal toxicity of (4-phenylcoumarin)acetanilide derivatives with a carboxylic acid moiety.

PubMed

Ogino, Masaki; Nakada, Yoshihisa; Negoro, Nobuyuki; Itokawa, Shigekazu; Nishimura, Satoshi; Sanada, Tsukasa; Satomi, Tomoko; Kita, Shunbun; Kubo, Kazuki; Marui, Shogo

2011-01-01

As a part of our research for novel potent and orally available acyl-CoA: cholesterol acyltransferase (ACAT) inhibitors that can be used as anti-atherosclerotic agents, we recently reported the discovery of the (4-phenylcoumarine)acetanilide derivative 1. However, compound 1 showed adrenal toxicity in animal models. In order to search for safer ACAT inhibitors that do not have adrenal toxicity, we examined the inhibitory activity of ACAT in human macrophage and adrenal cells. The introduction of a carboxylic acid moiety on the pendant phenyl ring and the adjustment of the lipophilicity led to the discovery of (2E)-3-[7-chloro-3-[2-[[4-fluoro-2-(trifluoromethyl)phenyl]amino]-2-oxoethyl]-6-methyl-2-oxo-2H-chromen-4-yl]phenyl]acrylic acid (21e), which showed potent ACAT inhibitory activity in macrophages and a selectivity of around 30-fold over adrenal cells. In addition, compound 21e showed high adrenal safety in guinea pigs.

Induction of Fetal Hemoglobin by Propionic and Butyric Acid Derivatives: Correlations between Chemical Structure and Potency of Hb F Induction1

PubMed Central

Liakopoulou, Effie; Li, Qiliang; Stamatoyannopoulos, George

2010-01-01

Short-chain fatty acids (C2-C9) induce fetal hemoglobin synthesis in primary cell cultures, primates, and patients. We carried out experiments to test whether relationships exist between chemical structure and the Hb F-inducing potential of several short-chain fatty acid derivatives. BFUe cultures were performed in the presence of propionic and butyric congeners, covering the full spectrum of substitutions of these molecules, including polar and non-polar groups, esters, and double bonds. We found that the fetal hemoglobin inducibility is related to the chemical structure of the inducing compound. This structure–activity relation depends on the length of carbon chain, the nature of the substitutions, and the position of more potent substitutions on the carbon chain. It appears that substitutions enhancing the inducibility of these compounds are (with decreasing potency): methyl > phenyl > hydroxy ≫ amino groups. Placement of these substitutions at a position distal to the carboxyl group enhances γ-globin inducibility. Presence of the carboxyl group is prerequisite for γ-globin inducibility. PMID:12482403

Carboxymethyl- and carboxyl-catechins from ripe Pu-er tea.

PubMed

Tian, Li-Wen; Tao, Mu-Ke; Xu, Min; Hu, Jing; Zhu, Hong-Tao; Xiong, Wen-Yong; Wang, Dong; Yang, Chong-Ren; Zhang, Ying-Jun

2014-12-17

Ripe Pu-er tea, a special microbial postfermented tea originated from Yunnan Province, China, since ancient times, is made from green Pu-er tea prepared from the leaves of Camellia sinensis var. assamica (Theaceae). Chemical investigation on thearubigin (n-BuOH-soluble) fraction of the commercial ripe Pu-er tea, led to the identification of four new flavan-3-ol derivatives, 8-carboxymethyl-(+)-catechin (1), 8-carboxymethyl-(+)-catechin methyl ester (2), 6-carboxymethyl-(+)-catechin (3), and 6-carboxyl-(-)-gallocatechin (4), together with 18 known compounds, including other three flavan-3-ol derivatives (5-7), 10 flavonoid glycosides (8-17), two hydrolyzable tannins (18 and 19), two quinic acid derivatives (20-21), and a purine alkaloid (22). Flavonoid glycosides 8-11 are reported from tea plants for the first time. The thearubigin fraction of ripe Pu-er tea was qualitatively analyzed by HPLC, and gallic acid was found to be the major component. Compounds 4, 6-17, 21 and 22 were tested for their acute activities on insulin sensitivity in differentiated 3T3-L1 adipocytes, but none of them showed significant bioactivity at a concentration of 10 μM.

40 CFR 721.10550 - Rare earth salt of a carboxylic acid (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Rare earth salt of a carboxylic acid... Specific Chemical Substances § 721.10550 Rare earth salt of a carboxylic acid (generic). (a) Chemical... as rare earth salt of a carboxylic acid (PMN P-05-324) is subject to reporting under this section for...

40 CFR 721.10550 - Rare earth salt of a carboxylic acid (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Rare earth salt of a carboxylic acid... Specific Chemical Substances § 721.10550 Rare earth salt of a carboxylic acid (generic). (a) Chemical... as rare earth salt of a carboxylic acid (PMN P-05-324) is subject to reporting under this section for...

Determination of carboxyl groups in wood fibers by headspace gas chromatography

Treesearch

X.-S. Chai; Q.X. Hou; J.Y. Zhu; S.-L. Chen; S.F. Wang; L. Lucia

2003-01-01

The phase reaction conversion (PRC) headspace gas chromatographic (HSGC) technique was employed to develop a method for the determination of the content of carboxyl groups in wood fibers. Acid treatment of the wood fibers using hydrochloric was applied to convert carboxyl groups to carboxyl acids. Bicarbonate solution is then used to react with carboxyl acids on the...

Process for producing peracids from aliphatic hydroxy carboxylic acids

DOEpatents

Chum, H.L.; Palasz, P.D.; Ratcliff, M.A.

1984-12-20

A process is described for producing peracids from lactic acid-containing solutions derived from biomass processing systems. It consists of adjusting the pH of the solution to about 8 to 9 and removing alkaline residue fractions therefrom to form a solution comprised substantially of lower aliphatic hydroxy acids. The solution is oxidized to produce volatile lower aliphatic aldehydes. The aldehydes are removed as they are generated and converted to peracids.

Identification and evaluation of anti-inflammatory properties of aqueous components extracted from sesame (Sesamum indicum) oil.

PubMed

Deme, Pragney; Narasimhulu, Chandrakala Aluganti; Parthasarathy, Sampath

2018-06-15

We previously reported that sesame oil (SO) has anti-inflammatory, anti-atherosclerotic and lipid lowering properties in vivo. Our recent studies have shown that, an aqueous extract of sesame oil (SOAE) has also anti-inflammatory and anti-atherosclerotic properties but with no lipid lowering effects. The extent of reduction in atherosclerosis led us to identify components of SOAE and evaluate their anti-inflammatory properties in vitro. Liquid chromatography mass spectrometric method was used to detect and identify components of SOAE. Methoxyphenol derivatives, short and long chain carboxylic acids, dicarboxylic acids, hydroxy and oxo- carboxylic acids were detected. To our surprise, sesamol and its derivatives (lignans), were not present in the SOAE. Among the identified, a combination of methoxy phenol compounds were selected and tested their ability to reduce LPS induced inflammatory gene expression. Monocyte derived macrophages/RAW 264.7 macrophages were pre-treated with these compounds for 2 h, followed by LPS stimulation for 24 h and pro-inflammatory gene expressions were analyzed. These methoxyphenol derivatives showed potent anti-inflammatory properties. In conclusion, the anti-inflammatory molecules associated with SO may contribute the anti-inflammatory and anti-atherosclerotic properties. Also, our results shed light for the development of SOAE based non-pharmacological therapeutics, nutritional supplements and health products for various inflammatory diseases in the future. Copyright © 2018 Elsevier B.V. All rights reserved.

Carbon dioxide utilization via carbonate-promoted C-H carboxylation.

PubMed

Banerjee, Aanindeeta; Dick, Graham R; Yoshino, Tatsuhiko; Kanan, Matthew W

2016-03-10

Using carbon dioxide (CO2) as a feedstock for commodity synthesis is an attractive means of reducing greenhouse gas emissions and a possible stepping-stone towards renewable synthetic fuels. A major impediment to synthesizing compounds from CO2 is the difficulty of forming carbon-carbon (C-C) bonds efficiently: although CO2 reacts readily with carbon-centred nucleophiles, generating these intermediates requires high-energy reagents (such as highly reducing metals or strong organic bases), carbon-heteroatom bonds or relatively acidic carbon-hydrogen (C-H) bonds. These requirements negate the environmental benefit of using CO2 as a substrate and limit the chemistry to low-volume targets. Here we show that intermediate-temperature (200 to 350 degrees Celsius) molten salts containing caesium or potassium cations enable carbonate ions (CO3(2-)) to deprotonate very weakly acidic C-H bonds (pKa > 40), generating carbon-centred nucleophiles that react with CO2 to form carboxylates. To illustrate a potential application, we use C-H carboxylation followed by protonation to convert 2-furoic acid into furan-2,5-dicarboxylic acid (FDCA)--a highly desirable bio-based feedstock with numerous applications, including the synthesis of polyethylene furandicarboxylate (PEF), which is a potential large-scale substitute for petroleum-derived polyethylene terephthalate (PET). Since 2-furoic acid can readily be made from lignocellulose, CO3(2-)-promoted C-H carboxylation thus reveals a way to transform inedible biomass and CO2 into a valuable feedstock chemical. Our results provide a new strategy for using CO2 in the synthesis of multi-carbon compounds.

Carbon dioxide utilization via carbonate-promoted C-H carboxylation

NASA Astrophysics Data System (ADS)

Banerjee, Aanindeeta; Dick, Graham R.; Yoshino, Tatsuhiko; Kanan, Matthew W.

2016-03-01

Using carbon dioxide (CO2) as a feedstock for commodity synthesis is an attractive means of reducing greenhouse gas emissions and a possible stepping-stone towards renewable synthetic fuels. A major impediment to synthesizing compounds from CO2 is the difficulty of forming carbon-carbon (C-C) bonds efficiently: although CO2 reacts readily with carbon-centred nucleophiles, generating these intermediates requires high-energy reagents (such as highly reducing metals or strong organic bases), carbon-heteroatom bonds or relatively acidic carbon-hydrogen (C-H) bonds. These requirements negate the environmental benefit of using CO2 as a substrate and limit the chemistry to low-volume targets. Here we show that intermediate-temperature (200 to 350 degrees Celsius) molten salts containing caesium or potassium cations enable carbonate ions (CO32-) to deprotonate very weakly acidic C-H bonds (pKa > 40), generating carbon-centred nucleophiles that react with CO2 to form carboxylates. To illustrate a potential application, we use C-H carboxylation followed by protonation to convert 2-furoic acid into furan-2,5-dicarboxylic acid (FDCA)—a highly desirable bio-based feedstock with numerous applications, including the synthesis of polyethylene furandicarboxylate (PEF), which is a potential large-scale substitute for petroleum-derived polyethylene terephthalate (PET). Since 2-furoic acid can readily be made from lignocellulose, CO32--promoted C-H carboxylation thus reveals a way to transform inedible biomass and CO2 into a valuable feedstock chemical. Our results provide a new strategy for using CO2 in the synthesis of multi-carbon compounds.

Biology-oriented drug synthesis (BIODS): In vitro β-glucuronidase inhibitory and in silico studies on 2-(2-methyl-5-nitro-1H-imidazol-1-yl)ethyl aryl carboxylate derivatives.

PubMed

Salar, Uzma; Khan, Khalid Mohammed; Taha, Muhammad; Ismail, Nor Hadiani; Ali, Basharat; Qurat-Ul-Ain; Perveen, Shahnaz; Ghufran, Mehreen; Wadood, Abdul

2017-01-05

Current study is based on the biology-oriented drug synthesis (BIODS) of 2-(2-methyl-5-nitro-1H-imidazol-1-yl)ethyl aryl carboxylate derivatives 1-26, by treating metronidazole with different aryl and hetero-aryl carboxylic acids in the presence of 1,1'-carbonyl diimidazole (CDI) as a coupling agent. Structures of all synthetic derivatives were confirmed with the help of various spectroscopic techniques such as EI-MS, 1 H -NMR and 13 C NMR. CHN elemental analyses were also found in agreement with the calculated values. Synthetic derivatives were evaluated to check their β-glucuronidase inhibitory activity which revealed that except few derivatives, all demonstrated good inhibition in the range of IC 50  = 1.20 ± 0.01-60.30 ± 1.40 μM as compared to the standard d-saccharic acid 1,4-lactone (IC 50  = 48.38 ± 1.05 μM). Compounds 1, 3, 4, 6, 9-19, and 21-24 were found to be potent analogs and showed superior activity than standard. Limited structure-activity relationship is suggested that the molecules having electron withdrawing groups like NO 2 , F, Cl, and Br, were displayed better activity than the compounds with electron donating groups such as Me, OMe and BuO. To verify these interpretations, in silico study was also performed, a good correlation was observed between bioactivities and docking studies. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Evidence for carboxyl-terminal processing and glycolipid-anchoring of human carcinoembryonic antigen.

PubMed

Takami, N; Misumi, Y; Kuroki, M; Matsuoka, Y; Ikehara, Y

1988-09-05

We have investigated the post-translational modification of carcinoembryonic antigen (CEA) for membrane-anchoring in QGP-1 cells derived from a human pancreatic carcinoma. Pulse-chase experiments with [3H]leucine demonstrated that CEA was initially synthesized as a precursor form with Mr 150,000 having N-linked high-mannose-type oligosaccharides, which was then converted to a mature form with Mr 200,000 containing the complex type sugar chains. The mature protein thus labeled was found to be released from the cell surface by treatment with phosphatidylinositol-specific phospholipase C, suggesting that CEA is a phosphatidylinositol-linked membrane protein. This was confirmed by metabolic incorporation into CEA of 3H-labeled compounds such as ethanolamine, myo-inositol, palmitic acid, and stearic acid. The 3H-labeled fatty acids incorporated were specifically removed from the protein by nitrous acid deamination as well as by phosphatidylinositol-specific phospholipase C treatment. Since the available cDNA sequence predicts that CEA contains a single methionine residue only in its carboxyl-terminal hydrophobic domain, processing of the carboxyl terminus was examined by pulse-chase experiments with [35S]methionine. It was found that CEA with Mr 150,000 was initially labeled with [35S]methionine but its radioactivity was immediately lost with chase. Taken together, these results suggest that CEA is anchored to the membrane by simultaneously occurring proteolysis of the carboxyl terminus and replacement by the glycophospholipid immediately after the synthesis.

Sorption of carboxylic acid from carboxylic salt solutions at pHs close to or above the pK[sub a] of the acid, with regeneration with an aqueous solution of ammonia or low-molecular-weight alkylamine

DOEpatents

King, C.J.; Tung, L.A.

1992-07-21

Carboxylic acids are sorbed from aqueous feedstocks at pHs close to or above the acids' pH[sub a] into a strongly basic organic liquid phase or onto a basic solid adsorbent or moderately basic ion exchange resin. The acids are freed from the sorbent phase by treating it with aqueous alkylamine or ammonia thus forming an alkylammonium or ammonium carboxylate which dewatered and decomposed to the desired carboxylic acid and the alkylamine or ammonia. 8 figs.

Regioselectivity of pyridine deprotonation in the gas phase.

PubMed

Schafman, Bonnie S; Wenthold, Paul G

2007-03-02

The regioselective deprotonation of pyridine in the gas phase has been investigated by using chemical reactivity studies. The mixture of regioisomers, trapped as carboxylates, formed in an equilibrium mixture is determined to result from 70-80% deprotonation in the 4-position, and 20-30% deprotonation at the 3-position. The ion formed by deprotonation in the 2-position is not measurably deprotonated at equilibrium because the ion is destabilized by lone-pair repulsion. From the composition of the mixture, the gas-phase acidities (DeltaH degrees acid) at the 4-, 3-, and 2-positions are determined to be 389.9 +/- 2.0, 391.2-391.5, and >391.5 kcal/mol, respectively. The relative acidities of the 4- and 3-positions are explained by using Hammett-Taft parameters, derived by using the measured gas-phase acidities of pyridine carboxylic acids. The values of sigmaF and sigmaR are -0.18 and 0.74, respectively, showing the infused nitrogen in pyridine to have a strong pi electron-withdrawing effect, but with little sigma-inductive effect.

The synthesis of ethacrynic acid thiazole derivatives as glutathione S-transferase pi inhibitors.

PubMed

Li, Ting; Liu, Guyue; Li, Hongcai; Yang, Xinmei; Jing, Yongkui; Zhao, Guisen

2012-04-01

Glutathione S-transferase pi (GSTpi) is a phase II enzyme which protects cells from death and detoxifies chemotherapeutic agents in cancer cells. Ethacrynic acid (EA) is a weak GSTpi inhibitor. Structure modifications were done to improve the ability of EA to inhibit GSTpi activity. Eighteen EA thiazole derivatives were designed and synthesized. Compounds 9a, 9b and 9c with a replacement of carboxyl group of EA by a heterocyclic thiazole exhibited improvement over EA to inhibit GSTpi activity. Copyright © 2012 Elsevier Ltd. All rights reserved.

Olfactory Sensitivity and Odor Structure-Activity Relationships for Aliphatic Carboxylic Acids in CD-1 Mice

PubMed Central

Can Güven, Selçuk; Laska, Matthias

2012-01-01

Using a conditioning paradigm, the olfactory sensitivity of CD-1 mice for a homologous series of aliphatic n-carboxylic acids (ethanoic acid to n-octanoic acid) and several of their isomeric forms was investigated. With all 14 odorants, the animals significantly discriminated concentrations as low as 0.03 ppm (parts per million) from the solvent, and with four odorants the best-scoring animals even detected concentrations as low as 3 ppt (parts per trillion). Analysis of odor structure-activity relationships showed that the correlation between olfactory detection thresholds of the mice for the unbranched carboxylic acids and carbon chain length can best be described as a U-shaped function with the lowest threshold values at n-butanoic acid. A significant positive correlation between olfactory detection thresholds and carbon chain length of the carboxylic acids with their branching next to the functional carboxyl group was found. In contrast, no such correlation was found for carboxylic acids with their branching at the distal end of the carbon chain relative to the functional carboxyl group. Finally, a significant correlation was found between olfactory detection thresholds and the position of the branching of the carboxylic acids. Across-species comparisons suggest that mice are more sensitive for short-chained (C2 to C4) aliphatic n-carboxylic acids than other mammalian species, but not for longer-chained ones (C5 to C8). Further comparisons suggest that odor structure-activity relationships are both substance class- and species-specific. PMID:22479594

Improvement in wettability of porous Si by carboxylate termination

NASA Astrophysics Data System (ADS)

Sakakibara, Masanori; Matsumoto, Kimihisa; Kamiya, Kazuhide; Kawabata, Shigeki; Inada, Mitsuru; Suzuki, Shinya

2018-02-01

The effects of the surface terminations of carboxylic acid and carboxylate on the hydrophilicity of porous Si were studied to observe the changes in the photoluminescence (PL) intensity of water-dispersed porous Si powder over time. Porous Si terminated by carboxylate was produced from carboxylic acid-terminated porous Si by a neutralization reaction with an alkali metal. After the neutralization of porous Si terminated by carboxylic acid, the formation of carboxylate-terminated porous Si was confirmed by observing the absorption peaks corresponding to Si-C and COO- from Fourier transform infrared (FT-IR) spectra. On the basis of changes in the PL intensity of porous Si over time, the hydrophilicity of porous Si terminated by carboxylate was determined to be higher than that of porous Si terminated by carboxylic acid. On the other hand, nonradiative recombination centers on the surface of carboxylate-terminated porous Si were formed during the neutralization process, which reduced the PL intensity. The PL from porous Si terminated by carboxylic acid and carboxylate was caused by the quantum size effect regardless of the termination molecules, which was confirmed by the wavelength dependence of the PL lifetime. Porous Si terminated by undecylenate is an effective material for applications such as bio-labels owing to its hydrophilicity and high PL stability.

Synthesis, Aqueous Reactivity, and Biological Evaluation of Carboxylic Acid Ester-Functionalized Platinum–Acridine Hybrid Anticancer Agents

PubMed Central

Graham, Leigh A.; Suryadi, Jimmy; West, Tiffany K.; Kucera, Gregory L.; Bierbach, Ulrich

2012-01-01

The synthesis of platinum–acridine hybrid agents containing carboxylic acid ester groups is described. The most active derivatives and the unmodified parent compounds showed up to 6-fold higher activity in ovarian cancer (OVCAR-3) and breast cancer (MCF-7, MDA-MB-23) cell lines than cisplatin. Inhibition of cell proliferation at nanomolar concentrations was observed in pancreatic (PANC-1) and non-small cell lung cancer cells (NSCLC, NCI-H460) of 80- and 150-fold, respectively. Introduction of the ester groups did not affect the cytotoxic properties of the hybrids, which form the same monofunctional–intercalative DNA adducts as the parent compounds, as demonstrated in a plasmid unwinding assay. In-line high-performance liquid chromatography and electrospray mass spectrometry (LC-ESMS) shows that the ester moieties undergo platinum-mediated hydrolysis in a chloride concentration-dependent manner to form carboxylate chelates. Potential applications of the chloride-sensitive ester hydrolysis as a self-immolative release mechanism for tumor-selective delivery of platinum–acridines are discussed. PMID:22871158

Synthesis, structure and stability of a chiral imine-based Schiff-based ligand derived from L-glutamic acid and its [Cu4] complex

NASA Astrophysics Data System (ADS)

Muche, Simon; Levacheva, Irina; Samsonova, Olga; Biernasiuk, Anna; Malm, Anna; Lonsdale, Richard; Popiołek, Łukasz; Bakowsky, Udo; Hołyńska, Małgorzata

2017-01-01

Studies of the stability of a ligand derived from L-glutamic acid and ortho-vanillin and its new [Cu4] complex are presented. The [Cu4] complex contains a heterocubane [CuII4O4] core and pendant carboxylic groups increasing its solubility in water, also under basic conditions. The stability of the complex in different solvents is confirmed with ESI-MS studies and such experiments as successful recrystallization. The complex is stable also under physiological conditions whereas the ligand is partly decomposed to L-glutamic acid and ortho-vanillin.

Design, synthesis, in silico and in vitro studies of novel 4-methylthiazole-5-carboxylic acid derivatives as potent anti-cancer agents.

PubMed

Kilaru, Ravendra Babu; Valasani, Koteswara Rao; Yellapu, Nanda Kumar; Osuru, Hari Prasad; Kuruva, Chandra Sekhar; Matcha, Bhaskar; Chamarthi, Naga Raju

2014-09-15

Since inhibitors of mucin onco proteins are potential targets for breast cancer therapy, a series of novel 4-methylthiazole-5-carboxylic acid (1) derivatives 3a-k were synthesized by the reaction of 1 with SOCl2 followed by different bases/alcohols in the presence of triethylamine. Once synthesized and characterized, their binding modes with MUC1 were studied by molecular docking analysis using Aruglab 4.0.1 and QSAR properties were determined using HyperChem. All synthesized compounds were screened for in vitro anti-breast cancer activity against MDA-MB-231 breast adenocarcinoma cell lines by Trypan-blue cell viability assay and MTT methods. Compounds 1, 3b, 3d, 3e, 3i and 3f showed good anti-breast cancer activity. Since 1 and 3d exhibited high potent activity against MDA-MB-231 cell lines, they show could be effective mucin onco protein inhibitors. Copyright © 2014 Elsevier Ltd. All rights reserved.

Using heteroaryl-lithium reagents as hydroxycarbonyl anion equivalents in conjugate addition reactions with (S,S)-(+)-pseudoephedrine as chiral auxiliary; enantioselective synthesis of 3-substituted pyrrolidines.

PubMed

Alonso, Beatriz; Ocejo, Marta; Carrillo, Luisa; Vicario, Jose L; Reyes, Efraim; Uria, Uxue

2013-01-18

We have developed an efficient protocol for carrying out the stereocontrolled formal conjugate addition of hydroxycarbonyl anion equivalents to α,β-unsaturated carboxylic acid derivatives using (S,S)-(+)-pseudoephedrine as chiral auxiliary, making use of the synthetic equivalence between the heteroaryl moieties and the carboxylate group. This protocol has been applied as key step in the enantioselective synthesis of 3-substituted pyrrolidines in which, after removing the chiral auxiliary, the heteroaryl moiety is converted into a carboxylate group followed by reduction and double nucleophilic displacement. Alternatively, the access to the same type of heterocyclic scaffold but with opposite absolute configuration has also been accomplished by making use of the regio- and diastereoselective conjugate addition of organolithium reagents to α,β,γ,δ-unsaturated amides derived from the same chiral auxiliary followed by chiral auxiliary removal, ozonolysis, and reductive amination/intramolecular nucleophilic displacement sequence.

[Pollution characteristics of organic acids in atmospheric particles during haze periods in autumn in Guangzhou].

PubMed

Tan, Ji-hua; Zhao, Jing-ping; Duan, Jing-chun; Ma, Yong-liang; He, Ke-bin; Yang, Fu-mo

2013-05-01

Total suspended particles (TSP), collected during a typical haze period in Guangzhou, were analyzed for the fatty acids (C12-C30) and low molecular weight dicarboxylic acids (C3-C9) using gas chromatography/mass spectrometry (GC/MS). The results showed that the concentration of total fatty and carboxylic acids was pretty high during the haze episode. The ratios of fatty acids and carboxylic acids in haze to those in normal days were 1.9 and 2.5, respectively. During the episode of the increasing pollution, the fatty acids and carboxylic acids at night (653 ng x m(-3)) was higher than that (487 ng x m(-3)) in days. After that, the level of fatty acids and carboxylic acids in days (412 ng x m(-3)) was higher than that (336 ng x m(-3)) at night. In general, the time-series of fatty acids and carboxylic acids was similar to that of the air particle and carbonaceous species, however, the trend of the ratio of fatty acids and carboxylic acids to organic carbon was opposite to that of air particle and carbonaceous species. This ratio decreased with the increase of the concentration of air particle and after the night of 27th, the ratio increased with the decrease in the concentration of air particle. The results showed that haze pollution had a significant inhibitory effect on the enrichment of fatty and carboxylic acids. Based on the ratio of malonate to succinate (C3/C4), it could be found that primary sources contribute more to the atmospheric fatty and carboxylic acids during the autumn haze pollution periods in Guangzhou.

Applications of Carboxylic Acid Reductases in Oleaginous Microbes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Resch, Michael G.; Linger, Jeffrey; McGeehan, John

2016-05-26

Carboxylic acid reductases (CARs) are recently emerging reductive enzymes for the direct production of aldehydes from biologically-produced carboxylic acids. Recent work has demonstrated that these powerful enzymes are able to reduce a very broad range of volatile- to long-chain fatty acids as well as aromatic acids. Here, we express four CAR enzymes from different fungal origins to test their activity against fatty acids commonly produced in oleaginous microbes. These in vitro results will inform metabolic engineering strategies to conduct mild biological reduction of carboxylic acids in situ, which is conventionally done via hydrotreating catalysis at high temperatures and hydrogen pressures.

[Inhibiting properties of stable nitroxyl radicals in reactions of linoleic acid and linoleyl alcohol oxidation catalyzed by 5-lipoxygenase].

PubMed

Kharchenko, O V; Kharitonenko, A I; Vovk, A I; Kukhar', V P; Babiĭ, L V; Khil'chevskiĭ, A N; Mel'nik, A K

2005-01-01

The inhibiting effects of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and its 4-substituted derivatives in reactions of linoleyl acid or linoleyl alcohol oxidation catalyzed by potato tuber 5-lipoxygenase were investigated. Inhibiting properties of stable nitroxyl radicals in presence of lubrol and SDS were reduced at the transition from TEMPO to 4-hydroxy-TEMPO or 4-amino-TEMPO and increased at use of adamantane-1-carboxylic or 3-methyladamantane-1-carboxylic acid 1-oxyl-2,2,6,6-tetramethylpiperidine-4-yl esters. Enzyme activity at saturating concentrations of inhibitor was not suppressed completely, and decreased up to the certain level determined by the substrate nature. The dependence of partial inhibition efficiency on rotational correlation time of stable nitroxides in model micellar systems were analysed. It was supposed that 5-lipoxygenase inhibition includes the interaction of hydrophobic nitroxide with radical intermediate formed in enzymatic process.

Crystallographic evidence for noncoplanar catalytic aspartic acids in plasmepsin II resides in the Protein Data Bank.

PubMed

Robbins, Arthur H; Dunn, Ben M; Agbandje-McKenna, Mavis; McKenna, Robert

2009-03-01

The carboxylate atoms of the two catalytic aspartic acid residues in aspartic proteases are nearly coplanar and in the uncomplexed form share an in-plane nucleophilic water molecule that is central to the mechanism of these enzymes. This note reports that while reviewing the electron-density maps derived from the deposited data for uncomplexed plasmepsin II from Plasmodium falciparum [Asojo et al. (2003), J. Mol. Biol. 327, 173-181; PDB code 1lf4], it was discovered that the aspartic acid residues in this structure should in fact be distinctly noncoplanar. The crystallographic model from the deposited coordinates has been re-refined against the 1.9 A resolution published diffraction data to an R(cryst) of 21.2% and an R(free) of 22.2%. The catalytic water molecule is present, but the plane of the carboxylate group of Asp214 is rotated by 66 degrees from its original position.

Aliphatic C-C Bond Cleavage in α-Hydroxy Ketones by a Dioxygen-Derived Nucleophilic Iron-Oxygen Oxidant.

PubMed

Bhattacharya, Shrabanti; Rahaman, Rubina; Chatterjee, Sayanti; Paine, Tapan K

2017-03-17

A nucleophilic iron-oxygen oxidant, formed in situ in the reaction between an iron(II)-benzilate complex and O 2 , oxidatively cleaves the aliphatic C-C bonds of α-hydroxy ketones. In the cleavage reaction, α-hydroxy ketones without any α-C-H bond afford a 1:1 mixture of carboxylic acid and ketone. Isotope labeling studies established that one of the oxygen atoms from dioxygen is incorporated into the carboxylic acid product. Furthermore, the iron(II) complex cleaves an aliphatic C-C bond of 17-α-hydroxyprogesterone affording androstenedione and acetic acid. The O 2 -dependent aliphatic C-C bond cleavage of α-hydroxy ketones containing no α-C-H bond bears similarity to the lyase activity of the heme enzyme, cytochrome P450 17A1 (CYP17A1). © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Aromatic polyketide synthases from 127 Fusarium: pas de deux for chemical diversity

USDA-ARS?s Scientific Manuscript database

Fusarium species collectively cause disease on almost all crop plants and produce numerous natural products (NPs), including mycotoxins, of great concern. Many Fusarium NPs are derived from polyketide synthases (PKSs), large enzymes that catalyze the condensation of simple carboxylic acids. To gain ...

Organic Reaction Mechanisms in the Sixth Form Part 2.

ERIC Educational Resources Information Center

Simpson, Peter

1989-01-01

Presents the mechanistic ideas underlying reactions between nucleophiles and carbonyl compounds as well as some popular misconceptions. Relates reactions of carboxylic acid derivatives to those of aldehydes and ketones. Discusses leaving group ability and the ability of carbonyl oxygen to accept a negative charge. (Author/MVL)

40 CFR 180.426 - 2-[4,5-Dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinoline carboxylic acid...

Code of Federal Regulations, 2010 CFR

2010-07-01

...-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinoline carboxylic acid; tolerance for residues. 180.426 Section 180...-Dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinoline carboxylic acid; tolerance for...)-5-oxo-1H-imidazol-2-yl]-3-quinoline carboxylic acid, in or on the raw agricultural commodity soybean...

Linking microbial community structure and product spectrum of rice straw fermentation with undefined mixed culture

NASA Astrophysics Data System (ADS)

Ai, Binling; Chi, Xue; Meng, Jia; Sheng, Zhanwu; Zheng, Lili; Zheng, Xiaoyan; Li, Jianzheng

2017-12-01

Undefined mixed culture-based fermentation is an alternative strategy for biofuels and bioproducts production from lignocellulosic biomass without supplementary cellulolytic enzymes. Mixed culture produces mixed carboxylates. To estimate the relationship between microbial community structure and product spectrum, carboxylate production was initiated by mixed cultures with different microbial community structure. All the inoculum cultures were derived from the same enrichment culture from the combination of cattle manure, pig manure compost, corn field soil and rotten wood. Due to the differences in the preparation method and culture time, the inoculum cultures for batch fermentation had high similarity in microbial community structure, while the community structure of each inoculum culture for repeated batch fermentation differed from that of another. The inoculum cultures with similar community structure led to a similar product spectrum. In batch fermentation, the selectivity of main product butyric acid stabilized around 76%. The inoculum cultures with different community structures resulted in different product spectra. In repeated batch fermentation, the butyric acid content gradually decreased to 27%, and the by-product acetic acid content steadily increased to 56%. The other by-products including propionic, valeric and caproic acids were also increased. It is deduced that keeping the microbial community structure stable makes the basic and key precondition for steady production of specific carboxylic acid with undefined mixed culture.

Bioeconomy Initiative at MBI International

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kleff, Susanne, Ph.D.

Di-carboxylic acids have the potential to replace petrochemicals used in the polymer industry (Werpy and Petersen, 2004). MBI developed a process for the production of succinic acid using a proprietary organism. During this work MBI assessed the feasibility to produce other carboxylic acids either using A. succinogenes or other organisms. The development of recombinant A. succinogenes strain derivatives for a mono-carboxylic acid through over-expression of enzymatic activities was successful. Fermentations achieved titers of 58 g/L for this organic acid. Recombinant strains that produced the same acid, but a different stereoisomer, reached titers of 10 g/L. Attempts to increase the titersmore » for this isomer as well as other organic acids were unsuccessful. MBI is looking for commercial partners to pursue the development of recombinant A. succinogenes strains for the production of other organic acids. Attempts to develop recombinant strains of A. succinogenes for fumaric acid production through introduction of various antisense RNA constructs were unsuccessful. Alternative suitable organisms were evaluated and Rhizopus oryzae, a natural fumaric acid producer with potential for process improvements, was selected. A novel fermentation and one-step recovery process was developed that allowed capture of IP, produced titers of >80 g/L with a productivity of 1.8 g/L-h and 57% (g/g glucose) yield. The process was scaled to 2000 L pilot scale. The economic analysis projected a production cost of 72 c/lb. Recycling and re-use of the base was demonstrated and incorporated into the process. The ability of the organism to produce fumaric acid from other carbon sources and biomass hydrolysate was demonstrated. The production of other organic acids was evaluated and techno-economic de-risking roadmap documents were prepared.« less

Synthesis and biological evaluation of pyrazolylthiazole carboxylic acids as potent anti-inflammatory-antimicrobial agents.

PubMed

Khloya, Poonam; Kumar, Satish; Kaushik, Pawan; Surain, Parveen; Kaushik, Dhirender; Sharma, Pawan K

2015-03-15

Current Letter presents design, synthesis and biological evaluation of a novel series of pyrazolylthiazole carboxylates 1a-1p and corresponding acid derivatives 2a-2p. All 32 novel compounds were tested for their in vivo anti-inflammatory activity by carrageenan-induced rat paw edema method as well as for in vitro antimicrobial activity. All the tested compounds exhibited excellent AI activity profile. Three compounds 1p (R=Cl, R(1)=Cl), 2c (R=H, R(1)=F) and 2n (R=Cl, R(1)=OCH3) were identified as potent anti-inflammatory agents exhibiting edema inhibition of 93.06-89.59% which is comparable to the reference drug indomethacin (91.32%) after 3h of carrageenan injection while most of the other compounds displayed inhibition ⩾80%. In addition, pyrazolylthiazole carboxylic acids (2a-2p) also showed good antimicrobial profile. Compound 2h (R=OCH3, R(1)=Cl) showed excellent antimicrobial activity (MIC 6.25μg/mL) against both Gram positive bacteria comparable with the reference drug ciprofloxacin (MIC 6.25μg/mL). Copyright © 2015 Elsevier Ltd. All rights reserved.

Cloning and characterization of cDNAs encoding human gastrin-releasing peptide.

PubMed Central

Spindel, E R; Chin, W W; Price, J; Rees, L H; Besser, G M; Habener, J F

1984-01-01

We have prepared and cloned cDNAs derived from poly(A)+ RNA from a human pulmonary carcinoid tumor rich in immunoreactivity to gastrin-releasing peptide, a peptide closely related in structure to amphibian bombesin. Mixtures of synthetic oligodeoxyribonucleotides corresponding to amphibian bombesin were used as hybridization probes to screen a cDNA library prepared from the tumor RNA. Sequencing of the recombinant plasmids shows that human gastrin-releasing peptide (hGRP) mRNA encodes a precursor of 148 amino acids containing a typical signal sequence, hGRP consisting of 27 or 28 amino acids, and a carboxyl-terminal extension peptide. hGRP is flanked at its carboxyl terminus by two basic amino acids, following a glycine used for amidation of the carboxyl-terminal methionine. RNA blot analyses of tumor RNA show a major mRNA of 900 bases and a minor mRNA of 850 bases. Blot hybridization analyses using human genomic DNA are consistent with a single hGRP-encoding gene. The presence of two mRNAs encoding the hGRP precursor protein in the face of a single hGRP gene raises the possibility of alternative processing of the single RNA transcript. Images PMID:6207529

Occurrence of an Unusual Hopanoid-containing Lipid A Among Lipopolysaccharides from Bradyrhizobium Species*

PubMed Central

Komaniecka, Iwona; Choma, Adam; Mazur, Andrzej; Duda, Katarzyna A.; Lindner, Buko; Schwudke, Dominik; Holst, Otto

2014-01-01

The chemical structures of the unusual hopanoid-containing lipid A samples of the lipopolysaccharides (LPS) from three strains of Bradyrhizobium (slow-growing rhizobia) have been established. They differed considerably from other Gram-negative bacteria in regards to the backbone structure, the number of ester-linked long chain hydroxylated fatty acids, as well as the presence of a tertiary residue that consisted of at least one molecule of carboxyl-bacteriohopanediol or its 2-methyl derivative. The structural details of this type of lipid A were established using one- and two-dimensional NMR spectroscopy, chemical composition analyses, and mass spectrometry techniques (electrospray ionization Fourier-transform ion cyclotron resonance mass spectrometry and MALDI-TOF-MS). In these lipid A samples the glucosamine disaccharide characteristic for enterobacterial lipid A was replaced by a 2,3-diamino-2,3-dideoxy-d-glucopyranosyl-(GlcpN3N) disaccharide, deprived of phosphate residues, and substituted by an α-d-Manp-(1→6)-α-d-Manp disaccharide substituting C-4′ of the non-reducing (distal) GlcpN3N, and one residue of galacturonic acid (d-GalpA) α-(1→1)-linked to the reducing (proximal) amino sugar residue. Amide-linked 12:0(3-OH) and 14:0(3-OH) were identified. Some hydroxy groups of these fatty acids were further esterified by long (ω-1)-hydroxylated fatty acids comprising 26–34 carbon atoms. As confirmed by mass spectrometry techniques, these long chain fatty acids could form two or three acyloxyacyl residues. The triterpenoid derivatives were identified as 34-carboxyl-bacteriohopane-32,33-diol and 34-carboxyl-2β-methyl-bacteriohopane-32,33-diol and were covalently linked to the (ω-1)-hydroxy group of very long chain fatty acid in bradyrhizobial lipid A. Bradyrhizobium japonicum possessed lipid A species with two hopanoid residues. PMID:25371196

Structure and thermotropic phase behavior of sodium and potassium carboxylate ionomers

NASA Astrophysics Data System (ADS)

Mantsch, H. H.; Weng, S. F.; Yang, P. W.; Eysel, H. H.

1994-07-01

A molecular complex is formed between long-chain carboxylic acids and their alkali salts in a 1 : 1 mixture. These so-called "acid soaps" or carboxylate ionomers have multilamellar bilayer-type structures in solid state, which are retained in the presence of excess water, resembling the dispersions (gels) formed by typical two-chain amphiphiles, e.g. lipids. The special arrangement of hydrogen-bonded pairs of carboxylic acid and carboxylate groups into a unique "head-group" is supported by frequency shifts and partial or total disappearance of the characteristic vibrations of carboxylic acid dimers and of carboxylate groups. The existence of well-ordered hydrocarbon chains is demonstrated by the existence and polarization properties of the methylene rocking and wagging propagation modes. The gel to liquid-crystal phase transition of the hydrated acid soaps shows practically no cation dependence, unlike the corresponding phase transition in neutral soaps which varies considerably with the nature of the counterion. There is spectroscopic evidence to suggest a cooperative process that involves "melting" of the alkyl chains and disintegration of the hydrogen-bonded carboxylate—carboxylic acid complex, followed by a cation-dependent equilibrium that favors the formation of acid dimers at elevated temperatures and some form of hydrogen-bonded ion pair aggregates at intermediate temperatures.

Synthesis and characterization of bifunctional surfaces with tunable functional group pairs

NASA Astrophysics Data System (ADS)

Galloway, John M.; Kung, Mayfair; Kung, Harold H.

2016-06-01

Grafting of pairs of functional groups onto a silica surface was demonstrated by tethering both terminals of an organochlorosilane precursor molecule, Cl2(CH3)Si(CH2)4(CO)(OSi(i-Pr)2)(CH2)2Si(CH3)Cl2, that possess a cleavable silyl ester bond, onto a silica surface. Hydrolytic cleavage of the silyl ester bond of the grafted molecule resulted in the generation of organized pairs of carboxylic acid and organosilanol groups. This organosilanol moiety was easily transformed into other functional groups through condensation reactions to form, together with the neighboring acid group, pairs such as carboxylic acid/secondary amine, carboxylic acid/pyridine, and carboxylic acid/phosphine. In the case of carboxylic acid/amine pairing, there was evidence of the formation of amide. A sample grafted with amine-carboxylic acid pairs was three times more active (per free amine) than a sample without such pairs for the nitroaldol condensation of 4-nitrobenzaldehyde and nitromethane.

Prophylactic and Treatment Drugs for Organophosphorus Poisoning

DTIC Science & Technology

1990-08-01

Synthesis of e-Mercapto-a- aminocaproic Acid and Its S- Alkyl and N-Sulfanilyl Derivatives." Yuan C.E.; Shchukina, M.N. Zhur. Obshchei Khim, 1957, 27... acids , carbamates, 07 0 1,AT( Isynthes is. 19. BSTACT(Continue on rveberl of newcesary and odentify by block number) The program is directed at the...cis-4-chlorobuten-l-ol and 4-chlorobutanol, one alicylaryl disulfide, two chlo’oalky(aryl) carboxylic acids , i,3.5-tris-2’-chloroethylbernzene I and d

Effects of Prostacyclin, Indomethacin, and Heparin on Cerebral Blood Flow and Platelet Adhesion After Multifocal Ischemia of Canine Brain

DTIC Science & Technology

1988-06-01

Hoff IT: Sodium 5-(3’-pyridinyl- methyl)benzoilzran-2-carboxylate (U-63557A) potentiates pro- tective effect of intravenrous eicosapentaenoic acid on...PAF.3- Hydroxy acids and PAP are pro- on the vascular endothelium.2 Although we were unable duced by platelets during aggregation and are potent to...Pickard JD: Role of prostaglandins and arachidonic acid derivatives in the coupling of cerebral blood flow to cerebral metabolism. J Cereb Blood Flow

Decarboxylative Fluorination of Aliphatic Carboxylic Acids via Photoredox Catalysis.

PubMed

Ventre, Sandrine; Petronijevic, Filip R; MacMillan, David W C

2015-05-06

The direct conversion of aliphatic carboxylic acids to the corresponding alkyl fluorides has been achieved via visible light-promoted photoredox catalysis. This operationally simple, redox-neutral fluorination method is amenable to a wide variety of carboxylic acids. Photon-induced oxidation of carboxylates leads to the formation of carboxyl radicals, which upon rapid CO2-extrusion and F(•) transfer from a fluorinating reagent yield the desired fluoroalkanes with high efficiency. Experimental evidence indicates that an oxidative quenching pathway is operable in this broadly applicable fluorination protocol.

Synthesis of 24-phenyl-24-oxo steroids derived from bile acids by palladium-catalyzed cross coupling with phenylboronic acid. NMR characterization and X-ray structures.

PubMed

Mayorquín-Torres, Martha C; Romero-Ávila, Margarita; Flores-Álamo, Marcos; Iglesias-Arteaga, Martin A

2013-11-01

Palladium-catalyzed cross coupling of phenyboronic acid with acetylated bile acids in which the carboxyl functions have been activated by formation of a mixed anhydride with pivalic anhydride afforded moderate to good yield of 24-phenyl-24-oxo-steroids. Unambiguous assignments of the NMR signals were made with the aid of combined 1D and 2D NMR techniques. X-ray diffraction studies confirmed the obtained structures. Copyright © 2013 Elsevier Inc. All rights reserved.

Sorption of carboxylic acid from carboxylic salt solutions at PHS close to or above the pK.sub.a of the acid, with regeneration with an aqueous solution of ammonia or low-molecular-weight alkylamine

DOEpatents

King, C. Judson; Tung, Lisa A.

1992-01-01

Carboxylic acids are sorbed from aqueous feedstocks at pHs close to or above the acids' pH.sub.a into a strongly basic organic liquid phase or onto a basic solid adsorbent or moderately basic ion exchange resin. the acids are freed from the sorbent phase by treating it with aqueous alkylamine or ammonia thus forming an alkylammonium or ammonium carobxylate which dewatered and decomposed to the desired carboxylic acid and the alkylamine or ammonia.

Protonation of Excited State Pyrene-1-Carboxylate by Phosphate and Organic Acids in Aqueous Solution Studied by Fluorescence Spectroscopy

PubMed Central

Zelent, Bogumil; Vanderkooi, Jane M.; Coleman, Ryan G.; Gryczynski, Ignacy; Gryczynski, Zygmunt

2006-01-01

Pyrene-1-carboxylic acid has a pK of 4.0 in the ground state and 8.1 in the singlet electronic excited state. In the pH range of physiological interest (pH ∼5–8), the ground state compound is largely ionized as pyrene-1-carboxylate, but protonation of the excited state molecule occurs when a proton donor reacts with the carboxylate during the excited state lifetime of the fluorophore. Both forms of the pyrene derivatives are fluorescent, and in this work the protonation reaction was measured by monitoring steady-state and time-resolved fluorescence. The rate of protonation of pyrene-COO− by acetic, chloroacetic, lactic, and cacodylic acids is a function of ΔpK, as predicted by Marcus theory. The rate of proton transfer from these acids saturates at high concentration, as expected for the existence of an encounter complex. Trihydrogen-phosphate is a much better proton donor than dihydrogen- and monohydrogen-phosphate, as can be seen by the pH dependence. The proton-donating ability of phosphate does not saturate at high concentrations, but increases with increasing phosphate concentration. We suggest that enhanced rate of proton transfer at high phosphate concentrations may be due to the dual proton donating and accepting nature of phosphate, in analogy to the Grotthuss mechanism for proton transfer in water. It is suggested that in molecular structures containing multiple phosphates, such as membrane surfaces and DNA, proton transfer rates will be enhanced by this mechanism. PMID:16920831

Molecular Structures and Sorption Mechanisms of Biochars as Heterogeneous Carbon Materials

NASA Astrophysics Data System (ADS)

Chen, Baoliang; Chen, Zaiming; Xiao, Xin; Fang, Qile

2015-04-01

Surface functional groups such as carboxyl play a vital role in the environmental applications of biochar as a soil amendment. However, the quantification of oxygen-containing groups on a biochar surface still lacks systematical investigation. An integrated method combining chemical and spectroscopic techniques was established to quantitatively identify the chemical states, dissociation constants (pKa), and contents of oxygen-containing groups on dairy manure-derived biochars prepared at 100-700 °C. The dissociation pH of carboxyl groups on the biochar surface covered a wide range of pH values (pH 2-11), due to the varied structural micro-environments and chemical states. For low temperature biochars (≤350 °C), carboxyl existed not only as hydrogen-bonded carboxyl and unbonded carboxyl groups but also formed esters at the surface of biochars. The esters consumed OH‒ via saponification in the alkaline pH region and enhanced the dissolution of organic matter from biochars. For high temperature biochars (≥500 °C), esters came from carboxyl were almost eliminated via carbonization (ester pyrolysis), while lactones were developed. The surface density of carboxyl groups on biochars decreased sharply with the increase of the biochar-producing temperature, but the total contents of the surface carboxyls for different biochars were comparable (with a difference < 3-fold) as a result of the expanded surface area at high pyrolytic temperatures. Understanding the wide pKa ranges and the abundant contents of carboxyl groups on biochars is a prerequisite to recognition of the multi-functional applications and biogeochemical cycling of biochars. A schematic diagram for the dissociation of acid/base groups on biochar surfaces and their related functions was depicted. The protonated biochars favor inorganic anion adsorption and ionizable organic chemical sorption, while the deprotonated biochars favor cationic nutrient retention, heavy metal immobilization, and the release of dissolved materials. For low temperature biochars (i.e., DM100, DM250 and DM350), the acid/base group dissociation directly controls the pH buffering properties of biochars. The resulting surface charges regulate biochars in nutrient retention, sorption/immobilization of hazardous pollutants and biochar particle dispersing properties. Meanwhile, dissociation of acid/base groups affects carbon and silica biogeochemical cycling by regulating the release of organic matter from the cleavage of esters and dissolution of the Si-containing minerals. For high temperature biochars (i.e., DM500 and DM700), the effect of acid/base dissociation on organic matter dissolution is eliminated, but other functions are similar. CGs are the major acid/base groups on biochar surfaces. In field applications, such abundant CGs are worthy of concern in terms of multiple functions of biochars, such as soil pH adjustment, soil nutrient retention, and toxic metals immobilization.

New fluoroprostaglandin F(2alpha) derivatives with prostanoid FP-receptor agonistic activity as potent ocular-hypotensive agents.

PubMed

Nakajima, Tadashi; Matsugi, Takeshi; Goto, Wakana; Kageyama, Masaaki; Mori, Nobuaki; Matsumura, Yasushi; Hara, Hideaki

2003-12-01

To find new prostanoid FP-receptor agonists possessing potent ocular-hypotensive effects with minimal side effects, we evaluated the agonistic activities of newly synthesized prostaglandin F(2alpha) derivatives for the prostanoid FP-receptor both in vitro and in vivo. The iris constrictions induced by the derivatives and their effects on melanin content were examined using cat isolated iris sphincters and cultured B16 melanoma cells, respectively. The effects of derivative ester forms on miosis and intraocular pressure (IOP) were evaluated in cats and cynomolgus monkeys, respectively. Of these derivatives, 6 out of 12 compounds were more potent iris constrictors, with EC(50) values of 0.6 to 9.4 nM, than a carboxylic acid of latanoprost (EC(50)=13.6 nM). A carboxylic acid of latanoprost (100 microM) significantly increased the melanin content of cultured B16 melanoma cells, but some 15,15-difluoro derivatives, such as AFP-157 and AFP-172, did not. Topically applied AFP-168, AFP-169 and AFP-175 (isopropyl ester, methyl ester and ethyl ester forms, respectively, of AFP-172) induced miosis in cats more potently than latanoprost. AFP-168 (0.0005%) reduced IOP to the same extent as 0.005% latanoprost (for at least 8 h). These findings indicate that 15,15-difluoroprostaglandin F(2alpha) derivatives, especially AFP-168, have more potent prostanoid FP-receptor agonistic activities than latanoprost. Hence, AFP-168 may be worthy of further evaluation as an ocular-hypotensive agent.

Acid sorption regeneration process using carbon dioxide

DOEpatents

King, C. Judson; Husson, Scott M.

2001-01-01

Carboxylic acids are sorbed from aqueous feedstocks onto a solid adsorbent in the presence of carbon dioxide under pressure. The acids are freed from the sorbent phase by a suitable regeneration method, one of which is treating them with an organic alkylamine solution thus forming an alkylamine-carboxylic acid complex which thermally decomposes to the desired carboxylic acid and the alkylamine.

The Conversion of Carboxylic Acids to Ketones: A Repeated Discovery

ERIC Educational Resources Information Center

Nicholson, John W.; Wilson, Alan D.

2004-01-01

The conversion of carboxylic acids to ketones is a useful chemical transformation with a long history. Several chemists have claimed that they discovered the conversion of carboxylic acids to ketones yet in fact the reaction is actually known for centuries.

Carboxylate modified porous graphitic carbon: a new class of hydrophilic interaction liquid chromatography phases.

PubMed

Wahab, M Farooq; Ibrahim, Mohammed E A; Lucy, Charles A

2013-06-18

Stationary phases for hydrophilic interaction liquid chromatography (HILIC) are predominantly based on silica and polymer supports. We present porous graphitic carbon particles with covalently attached carboxylic acid groups (carboxylate-PGC) as a new HILIC stationary phase. PGC particles were modified by adsorbing the diazonium salt of 4-aminobenzoic acid onto the PGC, followed by reduction of the adsorbed salt with sodium borohydride. The newly developed carboxylate-PGC phase exhibits different selectivity than that of 35 HPLC columns, including bare silica, zwitterionic, amine, reversed, and unmodified PGC phases. Carboxylate-PGC is stable from pH 2.0 to 12.6, yielding reproducible retention even at pH 12.6. Characterization of the new phase is presented by X-ray photoelectron spectroscopy, thermogravimetry, zeta potentials, and elemental analysis. The chromatographic performance of carboxylate-PGC as a HILIC phase is illustrated by separations of carboxylic acids, nucleotides, phenols, and amino acids.

Formation and High-order Carboxylic Acids (RCOOH) in Interstellar Analogous Ices of Carbon Dioxide (CO2) and Methane(CH4)

NASA Astrophysics Data System (ADS)

Zhu, Cheng; Turner, Andrew M.; Abplanalp, Matthew J.; Kaiser, Ralf I.

2018-01-01

This laboratory study simulated the abiotic formation of carboxylic acids (RCOOH) in interstellar analogous ices of carbon dioxide (CO2) and methane (CH4) at 10 K upon exposure to energetic electrons. The chemical processing of the ices and the subsequent warm-up phase were monitored online and in situ, exploiting Fourier Transform Infrared Spectrometry and quadrupole mass spectrometry. Characteristic absorptions of functional groups of carboxylic acids (RCOOH) were observed in the infrared spectra of the irradiated ice. Two proposed reaction mechanisms replicated the kinetic profiles of the carboxylic acids along with the decay profile of the precursors during the irradiation via hydrocarbon formation, followed by carboxylation and/or through acetic acid along with mass growth processes of the alkyl chain. Mass spectra recorded during the warm-up phase demonstrated that these acids are distributed from acetic acid (CH3COOH) up to decanoic acid (C9H19COOH). High-dose irradiation studies (91 ± 14 eV) converted low-molecular-weight acids such as acetic acid (CH3COOH) and propionic acid (C2H5COOH) to higher-molecular-weight carboxylic acids, compared to low-dose irradiation studies (18 ± 3 eV). The traces of the {{{H}}}2{{C}}= {{C}}({OH}{)}2+ (m/z = 60) fragment—a link to linear carboxylic acids—implied that higher-order acids (C n H2n+1COOH, n ≥ 5) are likely branched, which correlates with the recent analysis of the structures of the monocarboxylic acids in the Murchison meteorite.

Aqueous infrared carboxylate absorbances: Aliphatic di-acids

USGS Publications Warehouse

Cabaniss, S.E.; Leenheer, J.A.; McVey, I.F.

1998-01-01

Aqueous attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra of 18 aliphatic di-carboxylic acids are reported as a function of pH. The spectra show isosbestic points and intensity changes which indicate that Beer's law is obeyed, and peak frequencies lie within previously reported ranges for aqueous carboxylates and pure carboxylic acids. Intensity sharing from the symmetric carboxylate stretch is evident in many cases, so that bands which are nominally due to alkyl groups show increased intensity at higher pH. The asymmetric stretch of the HA- species is linearly related to the microscopic acidity constant of the H2A species, with ??pK 2 intervening atoms). The results suggest that aqueous ATR-FTIR may be able to estimate 'intrinsic' pKa values of carboxylic acids, in addition to providing quantitative estimates of ionization. ?? 1998 Elsevier Science B.V. All rights reserved.

From molecular salt to pseudo CAB cocrystal: Expanding solid-state landscape of carboxylic acids based on charge-assisted COOH⋯COO- hydrogen bonds

NASA Astrophysics Data System (ADS)

Lou, Benyong; Perumalla, Sathyanarayana Reddy; Sun, Changquan Calvin

2015-11-01

Using three carboxylic acids, we show that the COOH⋯COO- synthon is robust for directing the cocrystallization between a carboxylic acid and a carboxylate of either the same or a chemically different molecule to form a CAB or pseudo CAB cocrystal, respectively. For a given carboxylic acid and a counterion, only one salt could be prepared. However, additional one CAB cocrystals and two pseudo CAB cocrystals could be prepared based on the COOH⋯COO- synthon. The same synthon has the potential to enable the preparation of additional molecular pseudo CAB cocrystals using other chemically distinct carboxylic acids. This significantly increased number of solid forms highlights the values of charge-assisted synthons, such as COOH⋯COO-, in crystal engineering for expanding the range of material properties of a given molecule for optimum performance in product design.

Strong-acid, carboxyl-group structures in fulvic acid from the Suwannee River, Georgia. 1. Minor structures

USGS Publications Warehouse

Leenheer, J.A.; Wershaw, R. L.; Reddy, M.M.

1995-01-01

An investigation of the strong-acid characteristics (pKa 3.0 or less) of fulvic acid from the Suwannee River, Georgia, was conducted. Quantitative determinations were made for amino acid and sulfur-containing acid structures, oxalate half-ester structures, malonic acid structures, keto acid structures, and aromatic carboxyl-group structures. These determinations were made by using a variety of spectrometric (13C-nuclear magnetic resonance, infrared, and ultraviolet spectrometry) and titrimetric characterizations on fulvic acid or fulvic acid samples that were chemically derivatized to indicate certain functional groups. Only keto acid and aromatic carboxyl-group structures contributed significantly to the strong-acid characteristics of the fulvic acid; these structures accounted for 43% of the strong-acid acidity. The remaining 57% of the strong acids are aliphatic carboxyl groups in unusual and/or complex configurations for which limited model compound data are available.

Preparation of .alpha.,.beta.-unsaturated carboxylic acids and esters

DOEpatents

Gogate, Makarand Ratnakar; Spivey, James Jerry; Zoeller, Joseph Robert

1998-01-01

Disclosed is a process for the preparation of .alpha.,.beta.-unsaturated carboxylic acids and esters thereof which comprises contacting formaldehyde or a source of formaldehyde with a carboxylic acid, ester or anhydride in the presence of a catalyst comprising an oxide of niobium.

Preparation of {alpha},{beta}-unsaturated carboxylic acids and esters

DOEpatents

Gogate, M.R.; Spivey, J.J.; Zoeller, J.R.

1998-09-15

Disclosed is a process for the preparation of {alpha},{beta}-unsaturated carboxylic acids and esters thereof which comprises contacting formaldehyde or a source of formaldehyde with a carboxylic acid, ester or anhydride in the presence of a catalyst comprising an oxide of niobium.

Development of PEGylated carboxylic acid-modified polyamidoamine dendrimers as bone-targeting carriers for the treatment of bone diseases.

PubMed

Yamashita, Shugo; Katsumi, Hidemasa; Hibino, Nozomi; Isobe, Yugo; Yagi, Yumiko; Kusamori, Kosuke; Sakane, Toshiyasu; Yamamoto, Akira

2017-09-28

In this study, we aimed to develop a polyethylene glycol (PEG)-conjugated third generation polyamidoamine (PAMAM) dendrimer with multiple carboxylic acids as a bone-targeting carrier for the treatment of bone diseases. We conjugated PAMAM backbones to various carboxylic acids [aspartic acid (Asp), glutamic acid (Glu), succinic acid (Suc), or aconitic acid (Aco)] to obtain four different types of carboxylic acid-modified PAMAMs. PEG was covalently bound to carboxylic acid-modified PAMAMs to obtain PEGylated carboxylic acid-modified PAMAMs. In a tissue distribution study, the amount of 111 In-labeled unmodified PAMAM taken up by the bone after intravenous injection in mice was 11.3%. In contrast, the dose of 111 In-labeled PEG(5)-Asp-PAMAM, PEG(5)-Glu-PAMAM, PEG(5)-Suc-PAMAM, or PEG(5)-Aco-PAMAM that accumulated in the bone after injection was approximately 46.0, 15.6, 22.6, and 24.5%, respectively. The bone clearance rates of 111 In-labeled PEGylated carboxylic acid-modified PAMAMs were proportional to their affinities to hydroxyapatite and Ca 2+ . An intra-bone distribution study showed that fluorescein isothiocyanate-labeled PEG(5)-Asp-PAMAM predominantly accumulated on eroded and quiescent surfaces, a pattern associated with the pathogenesis of bone diseases, such as rheumatoid arthritis and osteoporosis. Our findings indicate that PEG(5)-Asp-PAMAM is a promising drug carrier for efficient drug targeting to the bones. Copyright © 2017 Elsevier B.V. All rights reserved.

High-level production of C-11-carboxyl-labeled amino acids. [For use in tumor and pancreatic imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Washburn, L. C.; Sun, T. T.; Byrd, B. L.

Carbon-11-labeled amino acids have significant potential as agents for positron tomographic functional imaging. We have developed a rapid, high-temperature, high-pressure modification of the Buecherer--Strecker amino acid synthesis and found it to be quite general for the production of C-11-carboxyl-labeled neutral amino acids. Production of C-11-carboxyl-labeled DL-tryptophan requires certain modifications in the procedure. Twelve different amino acids have been produced to date by this technique. Synthesis and chromatographic purification require approximately 40 min, and C-11-carboxyl-labeled amino acids have been produced in yields of up to 425 mCi. Two C-11-carboxyl-labeled amino acids are being investigated clinically for tumor scanning and two othersmore » for pancreatic imaging. Over 120 batches of the various agents have been produced for clinical use over a three-year period.« less

New trends and applications in carboxylation for isotope chemistry.

PubMed

Bragg, Ryan A; Sardana, Malvika; Artelsmair, Markus; Elmore, Charles S

2018-05-08

Carboxylations are an important method for the incorporation of isotopically labeled 14 CO 2 into molecules. This manuscript will review labeled carboxylations since 2010 and will present a perspective on the potential of recent unlabeled methodology for labeled carboxylations. The perspective portion of the manuscript is broken into 3 major sections based on product type, arylcarboxylic acids, benzylcarboxylic acids, and alkyl carboxylic acids, and each of those sections is further subdivided by substrate. © 2018 AstraZeneca. Journal of Labelled Compounds and Radiopharmaceuticals Published by John Wiley & Sons, Ltd.

Decarboxylative Fluorination of Aliphatic Carboxylic Acids via Photoredox Catalysis

PubMed Central

Ventre, Sandrine; Petronijevic, Filip R.; MacMillan, David W. C.

2016-01-01

The direct conversion of aliphatic carboxylic acids to the corresponding alkyl fluorides has been achieved via visible light-promoted photoredox catalysis. This operationally simple, redox-neutral fluorination method is amenable to a wide variety of carboxylic acids. Photon-induced oxidation of carboxylates leads to the formation of carboxyl radicals, which upon rapid CO2-extrusion and F• transfer from a fluorinating reagent yield the desired fluoroalkanes with high efficiency. Experimental evidence indicates that an oxidative quenching pathway is operable in this broadly applicable fluorination protocol. PMID:25881929

Carboxylic Acids Plasma Membrane Transporters in Saccharomyces cerevisiae.

PubMed

Casal, Margarida; Queirós, Odília; Talaia, Gabriel; Ribas, David; Paiva, Sandra

2016-01-01

This chapter covers the functionally characterized plasma membrane carboxylic acids transporters Jen1, Ady2, Fps1 and Pdr12 in the yeast Saccharomyces cerevisiae, addressing also their homologues in other microorganisms, as filamentous fungi and bacteria. Carboxylic acids can either be transported into the cells, to be used as nutrients, or extruded in response to acid stress conditions. The secondary active transporters Jen1 and Ady2 can mediate the uptake of the anionic form of these substrates by a H(+)-symport mechanism. The undissociated form of carboxylic acids is lipid-soluble, crossing the plasma membrane by simple diffusion. Furthermore, acetic acid can also be transported by facilitated diffusion via Fps1 channel. At the cytoplasmic physiological pH, the anionic form of the acid prevails and it can be exported by the Pdr12 pump. This review will highlight the mechanisms involving carboxylic acids transporters, and the way they operate according to the yeast cell response to environmental changes, as carbon source availability, extracellular pH and acid stress conditions.

Infrared Spectroscopy Determination of Lead Binding to Ethylenediaminotetraacetic Acid

NASA Astrophysics Data System (ADS)

Fitch, Alanah; Dragan, Simona

1998-08-01

In an attempt to improve a thematic lab sequence based on lead analysis of community derived samples, we have considered infrared spectroscopy as a method of determining the lead bound to ethylenediaminotetraacetic acid (EDTA). Students get acquainted with infrared spectroscopy by interpreting the spectra of EDTA, disodium ethylenediaminotetraacetate (Na2EDTA) and of lead(II) ethylenediaminotetraacetate (PbEDTA). Spectral characterization of the above compounds in the 1800-1500 cm-1 region gives information about the structural changes that sodium and lead binding to EDTA, respectively, produce. The spectra show the carboxylic carbonyl absorption band shifted from 1697 cm-1 to 1633 cm-1 in Na2EDTA, and two distinctive absorption bands at 1697 cm-1 and 1558 cm-1 in PbEDTA, the former being attributed to the "free" carboxylic group, as in EDTA, and the latter to the coordinated carboxylate with the bond order of less than 1.5 between the carbon and oxygen atoms. These features led us to the conclusion that the divalent Pb is tetra-coordinated having two covalent metal-nitrogen bonds and two ionic metal-carboxylate bonds. Based on the spectral differences between PbEDTA and EDTA, we have developed a method to quantitate the amount of lead bound to EDTA by simply comparing the peak height of the most prominent peaks in the 1800-1550 cm-1 region. A potential application of this method could be determination of lead extracted by binding it to ethylenediaminotetraacetic acid, excess EDTA being added.

40 CFR 721.4663 - Fluorinated carboxylic acid alkali metal salts.

Code of Federal Regulations, 2011 CFR

2011-07-01

... metal salts. 721.4663 Section 721.4663 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.4663 Fluorinated carboxylic acid alkali metal salts. (a) Chemical... fluorinated carboxylic acid alkali metal salts (PMNs P-95-979/980/981) are subject to reporting under this...

Effect of carboxyl-reduced heparin on the growth inhibition of bovine pulmonary artery smooth muscle cells

PubMed Central

G.Garg, Hari; Mrabat, Hicham; Yu, Lunyin; Freeman, Craig; Li, Boyangzi; Zhang, Fuming; Linhardt, Robert J.; Hales, Charles A.

2010-01-01

Heparin (HP) inhibits the proliferation of bovine pulmonary artery smooth muscle cells (BPASMC's), among other cell types in vitro. In order to develop a potential therapeutic agent to reverse vascular remodeling, we are involved in deciphering the relationship between the native HP structure and its antiproliferative potency. We have previously reported the influence of the molecular size and the effects of various O-sulfo and N-acetyl groups of HP on growth-inhibitory activity. In this study, to understand the influence of carboxyl groups in the HP structure required for endogenous activity, a chemically modified derivative of native HP was prepared by converting the carboxyl groups of hexuronic acid residues in HP to primary hydroxyl groups. This modification procedure involves the treatment of HP with N-(3-dimethylaminopropyl)-N-ethylcarbodiimide followed by reduction with NaBH4 to yield carboxyl-reduced heparin (CR-HP). When compared to the antiproliferative potency of native HP on cultured BPASMC's at three dose levels (1, 10, and 100 μg/mL), the CR-HP showed significantly less potency at all the doses. These results suggest that hexuronic acid residues in both major and variable sequences in HP are essential for the antiproliferative properties of native HP. PMID:20399420

Polythermal investigation of viscosity of solution of metal carboxylates in VIK-grade mixed carboxylic acids: Yttrium and gadolinium carboxylates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mezhov, E.A.; Samatov, A.V.; Troyanovskii, L.V.

Kinematic viscosities have been measured for solutions of yttrium and gadolinium carboxylates in grade VIK mixed carboxylic acids (MCA). It has been established that the optimal fluidity of these metal carboxylate solutions for application to articles is reached at 333 K. A regression model has been developed to describe the concentration and temperature dependences of the viscosity of yttrium- and gadolinium-containing MCA solutions. 2 refs., 3 tabs.

Metal adsorption onto bacterial surfaces: development of a predictive approach

NASA Astrophysics Data System (ADS)

Fein, Jeremy B.; Martin, Aaron M.; Wightman, Peter G.

2001-12-01

Aqueous metal cation adsorption onto bacterial surfaces can be successfully modeled by means of a surface complexation approach. However, relatively few stability constants for metal-bacterial surface complexes have been measured. In order to determine the bacterial adsorption behavior of cations that have not been studied in the laboratory, predictive techniques are required that enable estimation of the stability constants of bacterial surface complexes. In this study, we use a linear free-energy approach to compare previously measured stability constants for Bacillus subtilis metal-carboxyl surface complexes with aqueous metal-organic acid anion stability constants. The organic acids that we consider are acetic, oxalic, citric, and tiron. We add to this limited data set by conducting metal adsorption experiments onto Bacillus subtilis, determining bacterial surface stability constants for Co, Nd, Ni, Sr, and Zn. The adsorption behavior of each of the metals studied here was described well by considering metal-carboxyl bacterial surface complexation only, except for the Zn adsorption behavior, which required carboxyl and phosphoryl complexation to obtain a suitable fit to the data. The best correlation between bacterial carboxyl surface complexes and aqueous organic acid anion stability constants was obtained by means of metal-acetate aqueous complexes, with a linear correlation coefficient of 0.97. This correlation applies only to unhydrolyzed aqueous cations and only to carboxyl binding of those cations, and it does not predict the binding behavior under conditions where metal binding to other bacterial surface site types occurs. However, the relationship derived in this study permits estimation of the carboxyl site adsorption behavior of a wide range of aqueous metal cations for which there is an absence of experimental data. This technique, coupled with the observation of similar adsorption behaviors across bacterial species (Yee and Fein, 2001), enables estimation of the effects of bacterial adsorption on metal mobilities for a large number of environmental and geologic applications.

Year-round records of gas and particulate carboxylic acids (formate and acetate) in the boundary layer at Dumont d'Urville (coastal Antarctica): Production of carboxylic acids from biogenic NMHC emissions from the Antarctic ocean

NASA Astrophysics Data System (ADS)

Legrand, M.; Preunkert, S.; Jourdain, B.

2003-04-01

Multiple year-round concentrations of acetic and formic acids were measured both in gas and aerosol phases at Dumont d'Urville (DDU, a coastal Antarctic site: 66^o40'S, 140^o01'E) by using mist chamber and aerosol filter sampling. Aerosol levels of the 2 carboxylates range from less than one ng m-3 in winter to 5--10 ng m-3 in summer. Comparison with gas phase concentrations shows that almost 99% of the 2 carboxylic acids are present in the gas phase. Concentrations of formic acid in the gas phase are minima in June--July (70 ng m-3) and increase regularly towards summer months when levels reach ˜400 ng m-3. Concentrations of acetic acid in the gas phase exhibit a more well-marked seasonal cycle with values remaining close to 50 ng m-3 from April to October and strongly increase during summer months (mean value of 800 ng m-3). Such a strong seasonal cycle of carboxylic acids in the high southern latitude marine boundary layer displays with observations made at numerous continental sites where a more weak seasonality is generally observed. It is suggested that carboxylic acids present at DDU mainly originate from biogenic emissions from the Antarctic ocean which are expected to closely follow annual cycle of the sea ice extent and solar radiation, affecting in particular photochemical production of alkenes from dissolved organic carbon released from phytoplancton. Summer levels of carboxylic acids are discussed in terms of air-sea fluxes of NMHCs and photochemical production of carboxylic acids from ozone-alkene reactions and HO_2 reaction with peroxyacetal radical in these poor NOx environments.

Supramolecular architectures in two 1:1 cocrystals of 5-fluorouracil with 5-bromothiophene-2-carboxylic acid and thiophene-2-carboxylic acid.

PubMed

Mohana, Marimuthu; Thomas Muthiah, Packianathan; McMillen, Colin D

2017-06-01

In solid-state engineering, cocrystallization is a strategy actively pursued for pharmaceuticals. Two 1:1 cocrystals of 5-fluorouracil (5FU; systematic name: 5-fluoro-1,3-dihydropyrimidine-2,4-dione), namely 5-fluorouracil-5-bromothiophene-2-carboxylic acid (1/1), C 5 H 3 BrO 2 S·C 4 H 3 FN 2 O 2 , (I), and 5-fluorouracil-thiophene-2-carboxylic acid (1/1), C 4 H 3 FN 2 O 2 ·C 5 H 4 O 2 S, (II), have been synthesized and characterized by single-crystal X-ray diffraction studies. In both cocrystals, carboxylic acid molecules are linked through an acid-acid R 2 2 (8) homosynthon (O-H...O) to form a carboxylic acid dimer and 5FU molecules are connected through two types of base pairs [homosynthon, R 2 2 (8) motif] via a pair of N-H...O hydrogen bonds. The crystal structures are further stabilized by C-H...O interactions in (II) and C-Br...O interactions in (I). In both crystal structures, π-π stacking and C-F...π interactions are also observed.

An efficient copper-catalyzed synthesis of anilines by employing aqueous ammonia.

PubMed

Zeng, Xin; Huang, Wenming; Qiu, Yatao; Jiang, Sheng

2011-12-21

Under the catalysis of CuI/2-carboxylic acid-quinoline-N-oxide, the cross coupling reactions between aryl iodides or bromides and aqueous ammonia proceed very well to afford N-unprotected aniline derivatives in excellent yields. This inexpensive catalytic system shows great functional group tolerance and excellent reaction selectivity.

Isolation of Chromanone and Isobenzofuran Derivatives from a Fungicolous Isolate of Epiccocum purpurascens

USDA-ARS?s Scientific Manuscript database

Chemical studies of an organic extract of Epicoccum purpurascens NRRL 37031, isolated from a wood decay fungus in Florida, led to the isolation of two new metabolites, 7-methoxy-4-oxo-chroman-5-carboxylic acid methyl ester (1) and 1,3-dihydro-5-methoxy-7-methylisobenzofuran (2). Two known isobenzof...

A Molecular docking study to predict enantioseparation of some chiral carboxylic acid derivatives by methyl-β-cyclodextrin

NASA Astrophysics Data System (ADS)

Nurhidayah, E. S.; Ivansyah, A. L.; Martoprawiro, M. A.; Zulfikar, M. A.

2018-05-01

A molecular docking study, using molecular mechanics calculations with Arguslab, was used to help predict the enantioseparation of some guest molecules of chiral carboxylic acid derivatives by heptakis-2,6-di-O-methyl-β-cyclodextrin (DIMEB) and heptakis-2,3,6-tri-O-methyl-β-cyclodextrin (TRIMEB) as host molecules. The small differences in the binding free energy values (ΔΔG) obtained from Arguslab did not indicate any significant enantioseparation. From the molecular docking simulation results, it is predicted that in the case of DIMEB as host molecule, R-enantiomer of Etodolac, Fenoprofen, Indoprofen, Ketorolac, and Naproxen will be eluted first than S-enantiomer; However, S-enantiomer of Carprofen, Flurbiprofen, Ketoprofen, Pirprofen, Proglumide, Sulindac, Surprofen, and Zaltoprofen will be eluted first than R-enantiomer by DIMEB as host molecule. When TRIMEB is used as a host molecule, R-enantiomer of Carprofen, Flurbiprofen, Indoprofen, Ketoprofen, Naproxen, Pirprofen, and Surprofen will be eluted first than S-enantiomer; However, S-enantiomer of Etodolac, Fenoprofen, Ketorolac, Proglumide, Sulindac and Zaltoprofen will be eluted first than R-enantiomer by TRIMEB as host molecule.

Spectral characterization of novel ternary zinc(II) complexes containing 1,10-phenanthroline and Schiff bases derived from amino acids and salicylaldehyde-5-sulfonates

NASA Astrophysics Data System (ADS)

Boghaei, Davar M.; Gharagozlou, Mehrnaz

2007-07-01

A series of new ternary zinc(II) complexes [Zn(L 1-10)(phen)], where phen is 1,10-phenanthroline and H 2L 1-10 = tridentate Schiff base ligands derived from the condensation of amino acids (glycine, L-phenylalanine, L-valine, L-alanine, and L-leucine) and salicylaldehyde-5-sulfonates (sodium salicylaldehyde-5-sulfonate and sodium 3-methoxy-salicylaldehyde-5-sulfonate), have been synthesized. The complexes were characterized by elemental analysis, IR, UV-vis, 1H NMR, and 13C NMR spectra. The IR spectra of the complexes showed large differences between νas(COO) and νs(COO), Δ ν ( νas(COO) - νs(COO)) of 191-225 cm -1, indicating a monodentate coordination of the carboxylate group. Spectral data showed that in these ternary complexes the zinc atom is coordinated with the Schiff base ligand acts as a tridentate ONO moiety, coordinating to the metal through its phenolic oxygen, imine nitrogen, and carboxyl oxygen, and also with the neutral planar chelating ligand, 1,10-phenanthroline, coordinating through nitrogens.

Conformational characterization of peptides rich in the cycloaliphatic C alpha,alpha-disubstituted glycine 1-aminocyclononane-1-carboxylic acid.

PubMed

Gatos, M; Formaggio, F; Crisma, M; Valle, G; Toniolo, C; Bonora, G M; Saviano, M; Iacovino, R; Menchise, V; Galdiero, S; Pedone, C; Benedetti, E

1997-01-01

A series of N- and C-protected, monodispersed homo-oligopeptides (to the pentamer level) from the cycloaliphatic C alpha,alpha-dialkylated glycine 1-aminocyclononane-1-carboxylic acid (Ac9c) and two Ala/Ac9c tripeptides have been synthesized by solution methods and fully characterized. The conformational preferences of all the model peptides were determined in deuterochloroform solution by FT-IR absorption and 1H-NMR. The molecular structures of the amino acid derivatives mCIAc-Ac9c-OH and Z-Ac9c-OtBu, the dipeptide pBrBz-(Ac9c)2-OtBu, the tetrapeptide Z-(Ac9c)4-OtBu, and the pentapeptide Z-(Ac9c)5-OtBu were determined in the crystal state by X-ray diffraction. Based on this information, the average geometry and the preferred conformation for the cyclononyl moiety of the Ac9c residue have been assessed. The backbone conformational data are strongly in favour of the conclusion that the Ac9c residue is a strong beta-turn and helix former. A comparison with the structural propensity of alpha-aminoisobutyric acid, the prototype of C alpha,alpha-dialkylated glycines, and the other extensively investigated members of the family of 1-aminocycloalkane-1-carboxylic acids (Acnc, with n = 3-8) is made and the implications for the use of the Ac9c residue in conformationally constrained analogues of bioactive peptides are briefly examined.

Phthalide derivatives with antifungal activities against the plant pathogens isolated from the liquid culture of Pestalotiopsis photiniae.

PubMed

Yang, Xiao-Long; Zhang, Su; Hu, Qiong-Bo; Luo, Du-Qiang; Zhang, Yan

2011-11-01

Three new phthalide derivatives (1-3) named 5-(3'-methyl-2'-butenyl)-2-hydroxy-3-methoxy-4-methylbenzoic acid (1), 5-(3'-carboxyl-3'-methyl-2E-allyloxy)-3-methoxy-4-methylphthalide (2) and 5-(3',3'-dimethylallyloxy)-2-methoxycarbonyl-3-methoxy-4-methylbenzoic acid (3) together with six known phthalide derivatives named 5-(3',3'-dimethylallyloxy)-3-methoxy-4-methylphthalide (4), zinnimidine (5), 5-(3',3'-dimethylallyloxy)-3-methoxy-4-methylphthalide (6), 5-(3',3'-dimethylallyloxy)-3-methoxy-4-methylphthalic acid (7), zinniol anhydride (8) and porriolide (9) were isolated from the liquid culture of the plant endophytic fungus Pestalotiopsis photiniae isolated from the Chinese Podocarpaceae plant Podocarpus macrophyllus. Their structures were elucidated by extensive spectroscopic analysis. Compounds 1-9 displayed significant antifungal activities against three plant pathogens.

Unexpectedly convenient and stereoselective synthesis of 4α-acyloxy-2-chloropodophyllotoxins in the presence of BF₃ ·Et₂O.

PubMed

Xu, Hui; Xiao, Xiao; Zhao, Xue-Fei; Guo, Yong; Yao, Xiao-Jun

2011-07-01

Twenty-one 4α-acyloxy-2-chloropodophyllotoxin derivatives (5a-u), whose C-4 spatial configuration was mainly stereocontrolled by the configuration of C-2 chlorine atom, were unexpectedly prepared by the reaction of 2-chloropodophyllotoxin with carboxylic acids in the presence of BF(3)·Et(2)O. Compared with ordinary esterifications of carboxylic acids mediated by the condensation agent, for example, N,N'-diisopropylcarbodiimide (DIC), the present method made the procedure for the preparation of 4α-acyloxy-2-chloropodophyllotoxins more convenient, practical and easy. Meanwhile, the insecticidal activity of compounds 5a-u was preliminarily evaluated against the pre-third-instar larvae of Mythimna separata Walker in vivo at the concentration of 1mg/mL. Copyright © 2011 Elsevier Ltd. All rights reserved.

Decarboxylative alkenylation

NASA Astrophysics Data System (ADS)

Edwards, Jacob T.; Merchant, Rohan R.; McClymont, Kyle S.; Knouse, Kyle W.; Qin, Tian; Malins, Lara R.; Vokits, Benjamin; Shaw, Scott A.; Bao, Deng-Hui; Wei, Fu-Liang; Zhou, Ting; Eastgate, Martin D.; Baran, Phil S.

2017-04-01

Olefin chemistry, through pericyclic reactions, polymerizations, oxidations, or reductions, has an essential role in the manipulation of organic matter. Despite its importance, olefin synthesis still relies largely on chemistry introduced more than three decades ago, with metathesis being the most recent addition. Here we describe a simple method of accessing olefins with any substitution pattern or geometry from one of the most ubiquitous and variegated building blocks of chemistry: alkyl carboxylic acids. The activating principles used in amide-bond synthesis can therefore be used, with nickel- or iron-based catalysis, to extract carbon dioxide from a carboxylic acid and economically replace it with an organozinc-derived olefin on a molar scale. We prepare more than 60 olefins across a range of substrate classes, and the ability to simplify retrosynthetic analysis is exemplified with the preparation of 16 different natural products across 10 different families.

Electron mobility enhancement in ZnO thin films via surface modification by carboxylic acids

NASA Astrophysics Data System (ADS)

Spalenka, Josef W.; Gopalan, Padma; Katz, Howard E.; Evans, Paul G.

2013-01-01

Modifying the surface of polycrystalline ZnO films using a monolayer of organic molecules with carboxylic acid attachment groups increases the field-effect electron mobility and zero-bias conductivity, resulting in improved transistors and transparent conductors. The improvement is consistent with the passivation of defects via covalent bonding of the carboxylic acid and is reversible by exposure to a UV-ozone lamp. The properties of the solvent used for the attachment are crucial because solvents with high acid dissociation constants (Ka) for carboxylic acids lead to high proton activities and etching of the nanometers-thick ZnO films, masking the electronic effect.

Antibacterial properties of 3 H-spiro[1-benzofuran-2,1'-cyclohexane] derivatives from Heliotropium filifolium.

PubMed

Urzúa, Alejandro; Echeverría, Javier; Rezende, Marcos C; Wilkens, Marcela

2008-10-01

A re-examination of cuticular components of Heliotropium filifolium allowed the isolation of four new compounds: 3'-hydroxy-2',2',6'-trimethyl-3H-spiro[1-benzo-furan-2,1'-cyclohexane]-5-carboxylic acid(2), methyl 3'-acetyloxy-2',2',6'-trimethyl-3H-spiro[1-benzofuran-2,1'-cyclohexane]-5-carboxylate (3), methyl 3'-isopentanoyloxy-2',2',6'-trimethyl-3H-spiro[1-benzofuran-2,1'-cyclohexane]-5-carboxylate (4) and methyl 3'-benzoyloxy-2',2',6'-trimethyl-3H-spiro[1-benzofuran-2,1'-cyclohexane]-5-carboxylate (5).Compounds 2-5 were identified by their spectroscopic analogies with filifolinol (1), and their structures confirmed by chemical correlation with 1. The antimicrobial properties of the compounds were tested against Gram positive and Gram negative bacteria. Some of them proved to be active against Gram positive, but inactive against Gram negative bacteria. In searching for structure-activity relationships from the obtained MIC values, lipophilicity was shown to be an important variable.

Effects on Polo-like Kinase 1 Polo-box Domain Binding Affinities of Peptides Incurred by Structural Variation at the Phosphoamino Acid Position

PubMed Central

Qian, Wenjian; Park, Jung-Eun; Liu, Fa; Lee, Kyung S.; Burke, Terrence R.

2012-01-01

Protein-protein interactions (PPIs) mediated by the polo-box domain (PBD) of polo-like kinase 1 (Plk1) serve important roles in cell proliferation. Critical elements in the high affinity recognition of peptides and proteins by PBD are derived from pThr/pSer-residues in the binding ligands. However, there has been little examination of pThr/pSer mimetics within a PBD context. Our current paper compares the abilities of a variety of amino acid residues and derivatives to serve as pThr/pSer replacements by exploring the role of methyl functionality at the pThr β–position and by replacing the phosphoryl group by phosphonic acid, sulfonic acid and carboxylic acids. This work sheds new light on structure activity relationships for PBD recognition of phosphoamino acid mimetics. PMID:22743087

A study of the relationship between the chemical structures and the fluorescence quantum yields of coumarins, quinoxalinones and benzoxazinones for the development of sensitive fluorescent derivatization reagents.

PubMed

Azuma, Kentaro; Suzuki, Sachiko; Uchiyama, Seiichi; Kajiro, Toshi; Santa, Tomofumi; Imai, Kazuhiro

2003-04-01

To develop new fluorescent derivatization reagents, we investigated the relationship between the chemical structures and the fluorescence quantum yields (phi(f)) of coumarins, quinoxalinones and benzoxadinones. Forty-six compounds were synthesized and their fluorescence spectra were measured in n-hexane, ethyl acetate, methanol and water. The energy levels of these compounds were calculated by combination of the semi-empirical AM1 and INDO/S (CI = all) methods. The deltaE(Tn(n,pi*), S1(pi,pi*)) (the energy gap between the Tn(n,pi*) and S1(pi,pi*) states) values were well correlated with the phi(f) values, which enables us to predict the phi(f) values from their chemical structures. Based on this relationship, 3-phenyl-7-N-piperazinoquinoxalin-2(1H)-one (PQ-Pz) and 7-(3-(S)-aminopyrrolidin-1-yl)-3-phenylquinoxalin-2-(1H)-one (PQ-APy) were developed as fluorescent derivatization reagents for carboxylic acids. The derivatives of the carboxylic acids with PQ-Pz and PQ-APy showed large phi(f) values even in polar solvents, suggesting that these reagents are suitable for the microanalysis of biologically important carboxylic acids by reversed phase HPLC.

Boron-containing amino carboxylic acid compounds and uses thereof

DOEpatents

Kabalka, George W.; Srivastava, Rajiv R.

2000-03-14

Novel compounds which are useful for boron neutron capture therapy (BNCT) are disclosed. The compounds comprise a stable boron-containing group and an aminocycloalkane carboxylic acid group or a boronated acyclic hydrocarbon-linked amino carboxylic acid. Methods for synthesis of the compounds and for use of the compounds in BNCT are disclosed.

HPLC-MS/MS methods for the determination of 52 perfluoroalkyl and polyfluoroalkyl substances in aqueous samples.

PubMed

Gremmel, Christoph; Frömel, Tobias; Knepper, Thomas P

2017-02-01

Two quantitative methods using high-performance liquid chromatography (HPLC) combined with triple quadrupole tandem mass spectrometry (MS/MS) were developed to determine perfluoroalkyl and polyfluoroalkyl substances (PFASs) in aqueous samples. The first HPLC-MS/MS method was applied to 47 PFASs of 12 different substance classes with acidic characteristics such as perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkane sulfonic acids (PFSAs), as well as precursor substances and biotransformation intermediates (e.g., unsaturated fluorotelomer carboxylic acids). In addition, 25 13 C-, 18 O-, and 2 H-labeled PFASs were used as internal standards in this method. The second HPLC-MS/MS method was applied to fluorotelomer alcohols (FTOHs) and perfluorooctane sulfonamidoethanols as these compounds have physicochemical properties different from those of the previous ones. Accuracy between 82% and 110% and a standard deviation in the range from 2% to 22% depending on the substances were determined during the evaluation of repeatability and precision. The method quantification limit after solid-phase extraction ranged from 0.3 to 199 ng/L depending on the analyte and matrix. The HPLC-MS/MS methods developed were suitable for the determination of PFASs in aqueous samples (e.g., wastewater treatment plant effluents or influents after solid-phase extraction). These methods will be helpful in monitoring campaigns to evaluate the relevance of precursor substances as indirect sources of perfluorinated substances in the environment. In one exemplary application in an industrial wastewater treatment plant, FTOHs were found to be the major substance class in the influent; in particular, 6:2-FTOH was the predominant compound in the industrial samples and accounted for 74% of the total PFAS concentration. The increase in the concentration of the transformation products of FTOHs in the corresponding effluent, such as fluorotelomer carboxylic acids, unsaturated fluorotelomer carboxylic acids, n:3 polyfluorinated saturated carboxylic acids (n indicates the number of nonfluorinated carbon atoms), and PFCAs, indicated biotransformation of FTOHs or their derivatives during wastewater treatment. However, only 33 mol% of the total amount of PFASs present in the influent was quantified in the corresponding effluent. Graphical abstract Method development of an HPLC-MS/MS multi-method for the determination of PFASs in aqueos samples.

Simple route for nano-hydroxyapatite properties expansion.

PubMed

Rojas, L; Olmedo, H; García-Piñeres, A J; Silveira, C; Tasic, L; Fraga, F; Montero, M L

2015-10-20

Simple surface modification of nano-hydroxyapatite, through acid-basic reactions, allows expanding the properties of this material. Introduction of organic groups such as hydrophobic alkyl chains, carboxylic acid, and amide or amine basic groups on the hydroxyapatite surface systematically change the polarity, surface area, and reactivity of hydroxyapatite without modifying its phase. Physical and chemical properties of the new derivative particles were analyzed. The biocompatibility of modified Nano-Hap on Raw 264.7 cells was also assessed.

Cinnamate:CoA ligase initiates the biosynthesis of a benzoate-derived xanthone phytoalexin in Hypericum calycinum cell cultures.

PubMed

Gaid, Mariam M; Sircar, Debabrata; Müller, Andreas; Beuerle, Till; Liu, Benye; Ernst, Ludger; Hänsch, Robert; Beerhues, Ludger

2012-11-01

Although a number of plant natural products are derived from benzoic acid, the biosynthesis of this structurally simple precursor is poorly understood. Hypericum calycinum cell cultures accumulate a benzoic acid-derived xanthone phytoalexin, hyperxanthone E, in response to elicitor treatment. Using a subtracted complementary DNA (cDNA) library and sequence information about conserved coenzyme A (CoA) ligase motifs, a cDNA encoding cinnamate:CoA ligase (CNL) was isolated. This enzyme channels metabolic flux from the general phenylpropanoid pathway into benzenoid metabolism. HcCNL preferred cinnamic acid as a substrate but failed to activate benzoic acid. Enzyme activity was strictly dependent on the presence of Mg²⁺ and K⁺ at optimum concentrations of 2.5 and 100 mM, respectively. Coordinated increases in the Phe ammonia-lyase and HcCNL transcript levels preceded the accumulation of hyperxanthone E in cell cultures of H. calycinum after the addition of the elicitor. HcCNL contained a carboxyl-terminal type 1 peroxisomal targeting signal made up by the tripeptide Ser-Arg-Leu, which directed an amino-terminal reporter fusion to the peroxisomes. Masking the targeting signal by carboxyl-terminal reporter fusion led to cytoplasmic localization. A phylogenetic tree consisted of two evolutionarily distinct clusters. One cluster was formed by CoA ligases related to benzenoid metabolism, including HcCNL. The other cluster comprised 4-coumarate:CoA ligases from spermatophytes, ferns, and mosses, indicating divergence of the two clades prior to the divergence of the higher plant lineages.

Photo-Responsive Soft Ionic Crystals: Ion-Pairing Assemblies of Azobenzene Carboxylates.

PubMed

Yamakado, Ryohei; Hara, Mitsuo; Nagano, Shusaku; Seki, Takahiro; Maeda, Hiromitsu

2017-07-12

This report delineates the design and synthesis of negatively charged azobenzene derivatives that form photo-responsive ion-pairing assemblies. The azobenzene carboxylates possessing aliphatic chains were prepared as photo-responsive anions that promote the formation of ion-pairing dimension-controlled assemblies, including mesophases, when used in conjunction with a tetrabutylammonium (TBA) cation. The photo-responsive properties of the ion pairs and the precursory carboxylic acids in the bulk state were examined by polarized optical microscopy (POM) and X-ray diffraction (XRD), demonstrating that liquid crystal (LC)-liquid and crystal-liquid phase transitions occurred, depending on the number and lengths of the aliphatic chains of each assembly. An ion pair exhibited photo-induced crystal-crystal phase transitions upon switching between two irradiation wavelengths (365/436 nm). © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structural environments of carboxyl groups in natural organic molecules from terrestrial systems. Part 2: 2D NMR spectroscopy

NASA Astrophysics Data System (ADS)

Deshmukh, Ashish P.; Pacheco, Carlos; Hay, Michael B.; Myneni, Satish C. B.

2007-07-01

Carboxyl groups are abundant in natural organic molecules (NOM) and play a major role in their reactivity. The structural environments of carboxyl groups in IHSS soil and river humic samples were investigated using 2D NMR (heteronuclear and homonuclear correlation) spectroscopy. Based on the 1H- 13C heteronuclear multiple-bond correlation (HMBC) spectroscopy results, the carboxyl environments in NOM were categorized as Type I (unsubstituted and alkyl-substituted aliphatic/alicyclic), Type II (functionalized carbon substituted), Type IIIa, b (heteroatom and olefin substituted), and Type IVa, b (5-membered heterocyclic aromatic and 6-membered aromatic). The most intense signal in the HMBC spectra comes from the Type I carboxyl groups, including the 2JCH and 3JCH couplings of unsubstituted aliphatic and alicyclic acids, though this spectral region also includes the 3JCH couplings of Type II and III structures. Type II and III carboxyls have small but detectable 2JCH correlations in all NOM samples except for the Suwannee River humic acid. Signals from carboxyls bonded to 5-membered aromatic heterocyclic fragments (Type IVa) are observed in the soil HA and Suwannee River FA, while correlations to 6-membered aromatics (Type IVb) are only observed in Suwannee River HA. In general, aromatic carboxylic acids may be present at concentrations lower than previously imagined in these samples. Vibrational spectroscopy results for these NOM samples, described in an accompanying paper [Hay M. B. and Myneni S. C. B. (2007) Structural environments of carboxyl groups in natural organic molecules from terrestrial systems. Part 1: Infrared spectroscopy. Geochim. Cosmochim. Acta (in press)], suggest that Type II and Type III carboxylic acids with α substituents (e.g., -OH, -OR, or -CO 2H) constitute the majority of carboxyl structures in all humic substances examined. Furoic and salicylic acid structures (Type IV) are also feasible fragments, albeit as minor constituents. The vibrational spectroscopy results also suggest that much of the "Type I" signal observed in the HMBC spectrum is due to carboxylic acid esters and possibly α-substituted alicyclic acids.

Determination of 1-aminocyclopropane-1-carboxylic acid in apple extracts by capillary electrophoresis with laser-induced fluorescence detection.

PubMed

Liu, Xin; Li, Dian-Fan; Wang, Yun; Lu, Ying-Tang

2004-12-17

A rapid and sensitive method for the determination of 1-aminocyclopropane-1-carboxylic acid (ACC) in apple tissues has been described. This method is based on the derivatization of ACC with 3-(2-furoyl)quinoline-2-carboxaldehyde (FQ), and separation and quantification of the resulting FQ-ACC derivative by capillary electrophoresis coupled to laser-induced fluorescence detection (CE-LIF). Our results indicated that ACC derivatized with FQ could be well separated from other interfering amino acids using 20 mM borate buffer (pH 9.35) containing 40 mM sodium dodecyl sulfate and 10 mM Brij 35. The linearity of ACC was determined in the range from 0.05 to 5 microM with a correlation of 0.9967. The concentration detection limit for ACC was 10 nM (signal-to-noise = 3). The sensitivity and selectivity of this described method allows the analysis of ACC in crude apple extracts without extra purification and enrichment procedure.

Effects of Terminal Sterilization on PEG-Based Bioresorbable Polymers Used in Biomedical Applications.

PubMed

Bhatnagar, Divya; Dube, Koustubh; Damodaran, Vinod B; Subramanian, Ganesan; Aston, Kenneth; Halperin, Frederick; Mao, Meiyu; Pricer, Kurt; Murthy, N Sanjeeva; Kohn, Joachim

2016-10-01

The effects of ethylene oxide (EO), vaporized hydrogen peroxide (VHP), gamma (γ) radiation, and electron-beam (E-beam) on the physiochemical and morphological properties of medical device polymers are investigated. Polymers with ether, carbonate, carboxylic acid, amide and ester functionalities are selected from a family of poly(ethylene glycol) (PEG) containing tyrosine-derived polycarbonates (TyrPCs) to include slow, medium, fast, and ultrafast degrading polymers. Poly(lactic acid) (PLA) is used for comparison. Molecular weight ( M w ) of all tested polymers decreases upon gamma and E-beam, and this effect becomes more pronounced at higher PEG content. Gamma sterilization increases the glass transition temperature of polymers with high PEG content. EO esterifies the carboxylic acid groups in desaminotyrosol-tyrosine (DT) and causes significant degradation. VHP causes hydroxylation of the phenyl ring, and hydrolytic degradation. This study signifies the importance of the chemical composition when selecting a sterilization method, and provides suggested conditions for each of the sterilization methods.

Synthesis and characterization of silver nanoparticles from (bis)alkylamine silver carboxylate precursors

NASA Astrophysics Data System (ADS)

Uznanski, Pawel; Zakrzewska, Joanna; Favier, Frederic; Kazmierski, Slawomir; Bryszewska, Ewa

2017-03-01

A comparative study of amine and silver carboxylate adducts [R1COOAg-2(R2NH2)] (R1 = 1, 7, 11; R2 = 8, 12) as a key intermediate in NPs synthesis is carried out via differential scanning calorimetry, solid-state FT-infrared spectroscopy, 13C CP MAS NMR, powder X-ray diffraction and X-ray photoelectron spectroscopy, and various solution NMR spectroscopies (1H and 13C NMR, pulsed field gradient spin-echo NMR, and ROESY). It is proposed that carboxyl moieties in the presence of amine ligands are bound to silver ions via chelating bidentate type of coordination as opposed to bridging bidentate coordination of pure silver carboxylates resulting from the formation of dimeric units. All complexes are packed as lamellar bilayer structures. Silver carboxylate/amine complexes show one first-order melting transition. The evidence presented in this study shows that phase behavior of monovalent metal carboxylates are controlled, mainly, by head group bonding. In solution, insoluble silver salt is stabilized by amine molecules which exist in dynamic equilibrium. Using (bis)amine-silver carboxylate complex as precursor, silver nanoparticles were fabricated. During high-temperature thermolysis, the (bis)amine-carboxylate adduct decomposes to produce silver nanoparticles of small size. NPs are stabilized by strongly interacting carboxylate and trace amounts of amine derived from the silver precursor interacting with carboxylic acid. A corresponding aliphatic amide obtained from silver precursor at high-temperature reaction conditions is not taking part in the stabilization. Combining NMR techniques with FTIR, it was possible to follow an original stabilization mechanism.

Synthesis of superparamagnetic iron oxide nanoparticles coated with a DDNP-carboxyl derivative for in vitro magnetic resonance imaging of Alzheimer's disease.

PubMed

Zhou, Jingting; Fa, Huanbao; Yin, Wei; Zhang, Jin; Hou, Changjun; Huo, Danqun; Zhang, Dong; Zhang, Haifeng

2014-04-01

Superparamagnetic iron oxide nanoparticles (SPIONs) have been proposed for use in magnetic resonance imaging as versatile ultra-sensitive nanoprobes for Alzheimer's disease imaging. In this work, we synthetized an efficient contrast agent of Alzheimer's disease using 1,1-dicyano-2-[6-(dimethylamino)naphthalene-2-yl]propene (DDNP) carboxyl derivative to functionalize the surface of SPIONs. The DDNP-SPIONs are prepared by conjugating DDNP carboxyl derivative to oleic acid-treated SPIONs through ligand exchange. The structure, size distribution and magnetic property were identified by IR, TGA-DTA, XRD, TEM, Zetasizer Nano and VSM. TEM and Zetasizer Nano observations indicated that the DDNP-SPIONs are relatively mono-dispersed spherical distribution with an average size of 11.7nm. The DDNP-SPIONs were then further analyzed for their MRI relaxation properties using MR imaging and demonstrated high T2 relaxivity of 140.57s(-1)FemM(-1), and the vitro experiment that DDNP-SPIONs binding to β-Amyloid aggregates were then investigated by fluorophotometry, the results showed that the combination had induced the fluorescence enhancement of the DDNP-SPIONs and displayed tremendous promise for use as a contrast agent of Alzheimer's disease in MRI. Copyright © 2014 Elsevier B.V. All rights reserved.

Separation of certain carboxylic acids utilizing cation exchange membranes

DOEpatents

Chum, H.L.; Sopher, D.W.

1983-05-09

A method of substantially separating monofunctional lower carboxylic acids from a liquid mixture containing the acids wherein the pH of the mixture is adjusted to a value in the range of from about 1 to about 5 to form protonated acids. The mixture is heated to an elevated temperature not greater than about 100/sup 0/C and brought in contact with one side of a perfluorinated cation exchange membrane having sulfonate or carboxylate groups or mixtures thereof with the mixture containing the protonated acids. A pressure gradient can be established across the membrane with the mixture being under higher pressure, so that protonated monofunctional lower carboxylic acids pass through the membrane at a substantially faster rate than the remainder of the mixture thereby substantially separating the acids from the mixture.

Separation of certain carboxylic acids utilizing cation exchange membranes

DOEpatents

Chum, Helena L.; Sopher, David W.

1984-01-01

A method of substantially separating monofunctional lower carboxylic acids from a liquid mixture containing the acids wherein the pH of the mixture is adjusted to a value in the range of from about 1 to about 5 to form protonated acids. The mixture is heated to an elevated temperature not greater than about 100.degree. C. and brought in contact with one side of a perfluorinated cation exchange membrane having sulfonate or carboxylate groups or mixtures thereof with the mixture containing the protonated acids. A pressure gradient can be established across the membrane with the mixture being under higher pressure, so that protonated monofunctional lower carboxylic acids pass through the membrane at a substantially faster rate than the remainder of the mixture thereby substantially separating the acids from the mixture.

Tris[(6S)-6-hy­droxy-4-epi-shikimic acid] monohydrate: an enanti­omerically pure hy­droxy­lated shikimic acid derived from methyl shikimate

PubMed Central

Griesbeck, Axel G.; Miara, Claus; Neudörfl, Jörg-M.

2012-01-01

The title compound, 3C7H10O6·H2O, is the enanti­omerically pure product of a multi-step synthesis from the enanti­omerically pure natural shikimic acid. The asymmetric unit contains three mol­ecules of the acid and one mol­ecule of water. The cyclo­hexene rings of the acids have half-chair conformations. The carboxyl­ate, the four hydroxide groups and the additional water mol­ecule form a complex three-dimensional hydrogen-bonding network. PMID:23284468

Comparison of Three Solid Phase Materials for the Extraction of Carboxylic Acids from River Water Followed by 2D GC × GC-TOFMS Determination

PubMed Central

Bosire, G. O.; Ngila, J. C.; Parshotam, H.

2016-01-01

The extraction and determination of aliphatic and aromatic carboxylic acids as well as their influence on the aromaticity and molecularity relationship of natural organic matter (NOM) in water are reported in this study. Three solid phase extraction (SPE) sorbents were used and their extraction efficiencies evaluated after chromatographic determinations (using gas chromatography with a time of flight mass spectrometer (GC × GC-TOFMS) and liquid chromatography with organic carbon detector (LC-OCD)). More than 42 carboxylic acids were identified in raw water from the Vaal River, which feeds the Lethabo Power Generation Station, South Africa, with cooling water. The aromatic carboxylic acid efficiency (28%) was achieved by using Strata™ X SPE while the highest aliphatic carboxylic acid efficiency (92.08%) was achieved by silica SPE. The hydrophobic nature of NOM in water depends on the nature of organic compounds in water, whether aromatic or aliphatic. The LC-OCD was used to assess the hydrophobicity levels of NOM as a function of these carboxylic acids in cooling water. The LC-OCD results showed that the aromatic nature of NOM in SPE filtered water followed the order Silica>Strata X>C-18. From the results, the hydrophobicity degree of the samples depended on the type and number of carboxylic acids that were removed by the SPE cartridges. PMID:27274730

Chemical and spectroscopic characterization of dissolved humic substances in a mangrove-fringed estuary in the eastern coast of Hainan Island, China

NASA Astrophysics Data System (ADS)

Zhang, Yaoling; Du, Jinzhou; Peng, Bo; Zhang, Fenfen; Zhao, Xin; Zhang, Jing

2013-03-01

Mangrove-derived dissolved organic matter (DOM) has an important effect on estuarine and coastal area on a large scale. In order to improve the understanding of origin, composition, and fate of DOM in mangrove-fringed estuarine and coastal areas, dissolved humic substances (DHS) were isolated from one mangrove pore-water sample and one near-shore seawater sample downstream the mangrove pore-water site in the eastern coast of Hainan Island, South China. Fulvic acids, humic acids and XAD-4 fractions were obtained from the two water samples by using a two-column array of XAD-8 and XAD-4 resins. Chemical and spectroscopic methods were used to analyze the features of these DHS. Compared to the mangrove pore-water DHS, the near-shore seawater DHS were found rich in 13C with lower C/N ratios and more aliphatic compounds and carbohydrates, but less aromatic structures and carboxyl groups. As for the three fractions of the two DHS, XAD-4 fractions contain more aliphatics, carbohydrates, carboxyl groups, and enrich in 13C with respect to both fulvic and humic acids. Photo-oxidation transformation and contribution from marine-derived DOM were considered as the main reasons resulted in the difference in compositional features for these DHS in this study.

Carboxylic acid accelerated formation of diesters

DOEpatents

Tustin, Gerald Charles; Dickson, Todd Jay

1998-01-01

This invention pertains to accelerating the rate of formation of 1,1-dicarboxylic esters from the reaction of an aldehyde with a carboxylic acid anhydride or a ketene in the presence of a non-iodide containing a strong Bronsted acid catalyst by the addition of a carboxylic acid at about one bar pressure and between about 0.degree. and 80.degree. C. in the substantial absence of a hydrogenation or carbonylation catalyst.

Carboxylic acid accelerated formation of diesters

DOEpatents

Tustin, G.C.; Dickson, T.J.

1998-04-28

This invention pertains to accelerating the rate of formation of 1,1-dicarboxylic esters from the reaction of an aldehyde with a carboxylic acid anhydride or a ketene in the presence of a non-iodide containing a strong Bronsted acid catalyst by the addition of a carboxylic acid at about one bar pressure and between about 0 and 80 C in the substantial absence of a hydrogenation or carbonylation catalyst.

Characterization and origin of polar dissolved organic matter from the Great Salt Lake

USGS Publications Warehouse

Leenheer, J.A.; Noyes, T.I.; Rostad, C.E.; Davisson, M.L.

2004-01-01

Polar dissolved organic matter (DOM) was isolated from a surface-water sample from the Great Salt Lake by separating it from colloidal organic matter by membrane dialysis, from less-polar DOM fractions by resin sorbents, and from inorganic salts by a combination of sodium cation exchange followed by precipitation of sodium salts by acetic acid during evaporative concentration. Polar DOM was the most abundant DOM fraction, accounting for 56% of the isolated DOM. Colloidal organic matter was 14C-age dated to be about 100% modern carbon and all of the DOM fractions were 14C-age dated to be between 94 and 95% modern carbon. Average structural models of each DOM fraction were derived that incorporated quantitative elemental and infrared, 13C-NMR, and electrospray/mass spectrometric data. The polar DOM model consisted of open-chain N-acetyl hydroxy carboxylic acids likely derived from N-acetyl heteropolysaccharides that constituted the colloidal organic matter. The less polar DOM fraction models consisted of aliphatic alicyclic ring structures substituted with carboxyl, hydroxyl, ether, ester, and methyl groups. These ring structures had characteristics similar to terpenoid precursors. All DOM fractions in the Great Salt Lake are derived from algae and bacteria that dominate DOM inputs in this lake.

Hydrogenation of carboxylic acids with a homogeneous cobalt catalyst.

PubMed

Korstanje, Ties J; van der Vlugt, Jarl Ivar; Elsevier, Cornelis J; de Bruin, Bas

2015-10-16

The reduction of esters and carboxylic acids to alcohols is a highly relevant conversion for the pharmaceutical and fine-chemical industries and for biomass conversion. It is commonly performed using stoichiometric reagents, and the catalytic hydrogenation of the acids previously required precious metals. Here we report the homogeneously catalyzed hydrogenation of carboxylic acids to alcohols using earth-abundant cobalt. This system, which pairs Co(BF4)2·6H2O with a tridentate phosphine ligand, can reduce a wide range of esters and carboxylic acids under relatively mild conditions (100°C, 80 bar H2) and reaches turnover numbers of up to 8000. Copyright © 2015, American Association for the Advancement of Science.

Biodiesel forming reactions using heterogeneous catalysis

NASA Astrophysics Data System (ADS)

Liu, Yijun

Biodiesel synthesis from biomass provides a means for utilizing effectively renewable resources, a way to convert waste vegetable oils and animal fats to a useful product, a way to recycle carbon dioxide for a combustion fuel, and production of a fuel that is biodegradable, non-toxic, and has a lower emission profile than petroleum-diesel. Free fatty acid (FFA) esterification and triglyceride (TG) transesterification with low molecular weight alcohols constitute the synthetic routes to prepare biodiesel from lipid feedstocks. This project was aimed at developing a better understanding of important fundamental issues involved in heterogeneous catalyzed biodiesel forming reactions using mainly model compounds, representing part of on-going efforts to build up a rational base for assay, design, and performance optimization of solid acids/bases in biodiesel synthesis. As FFA esterification proceeds, water is continuously formed as a byproduct and affects reaction rates in a negative manner. Using sulfuric acid (as a catalyst) and acetic acid (as a model compound for FFA), the impact of increasing concentrations of water on acid catalysis was investigated. The order of the water effect on reaction rate was determined to be -0.83. Sulfuric acid lost up to 90% activity as the amount of water present increased. The nature of the negative effect of water on esterification was found to go beyond the scope of reverse hydrolysis and was associated with the diminished acid strength of sulfuric acid as a result of the preferential solvation by water molecules of its catalytic protons. The results indicate that as esterification progresses and byproduct water is produced, deactivation of a Bronsted acid catalyst like H2SO4 occurs. Using a solid composite acid (SAC-13) as an example of heterogeneous catalysts and sulfuric acid as a homogeneous reference, similar reaction inhibition by water was demonstrated for homogeneous and heterogeneous catalysis. This similarity together with other comparisons between the catalytic behaviors of liquid and solid acids suggests a common mode of operation of their Bronsted acid sites in carrying out esterification of a carboxylic acid with alcohol. The hypothesized Eley-Rideal type heterogeneous reaction mechanism involving a nucleophilic attack between adsorbed carboxylic acid and unadsorbed alcohol as the rate-limiting step was found to fit well the experimental observations and successfully predict the esterification rate obtained with SAC-13 as reaction progresses. The SAC-13 catalysis assay was also extended to carboxylic acids of higher molecular weights. A set of carboxylic acids with various alkyl chain lengths was used to investigate the structural effect of reacting carboxylic acids on heterogeneous catalyzed esterification. It was found that the reactivity of carboxylic acids was controlled by steric factors as the alkyl chain linearly lengthened. Despite their increased hydrophobicity, large carboxylic acids hardly impacted the deactivating effect of water on Bronsted acid sites. However, catalyst reusability and regeneration showed significant dependency on the size of the carboxylic acid used. With the use of larger reacting carboxylic acids, SAC-13 underwent more significant activity loss in consecutive reaction cycles due to stronger adsorption of the larger organics in the polymeric domains of the Nafion resin. In parallel to the research activity on acid catalyzed esterification, the use of strong solid bases with organic functionality (quarternary ammonium, QN+) was investigated from a fundamental perspective. Using triacetin as a model compound for TG molecules, the effectiveness of this Bronsted base functionality in transesterification was demonstrated even at mild reaction conditions. But its catalytic behavior including catalyst selectivity and deactivation was significantly affected by the nature of the adopted support. A purposive design of the immobilizing matrix is expected to optimize the activity, selectivity, and stability of the QN+ groups, thus enhancing their applicability in practical biodiesel synthesis from lipid feedstocks. As the solid organic base-matrix composite catalyst remains to be better designed to fit the need of TG methanolysis, inorganic solid bases composed of metal oxides appear to be a more feasible choice given that their thermal robustness generally allows the achievement of sufficient activity by increasing reaction temperature and potentially permits a convenient regeneration by recalcination. A study dealing with the methanolysis of real lipid feedstock (poultry fat) was carried out using Mg-Al hydrotalcite derived catalysts. From a practical standpoint, the impact of a variety of operational variables on reaction, such as catalyst pretreatments, temperature, reactants molar ratio, and usage of co-solvent were addressed. As a result, biodiesel synthesis from poultry fat was successfully conducted by appropriately adjusting these variables. However, many underlying aspects associated with catalyst performance remain unexamined and unexplained.

Speciation of aqueous Ni(II)-carboxylate and Ni(II)-fulvic acid solutions: Combined ATR-FTIR and XAFS analysis

NASA Astrophysics Data System (ADS)

Strathmann, Timothy J.; Myneni, Satish C. B.

2004-09-01

Aqueous solutions containing Ni(II) and a series of structurally related carboxylic acids were analyzed using attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and Ni K-edge X-ray absorption fine structure spectroscopy (XAFS). XAFS spectra were also collected for solutions containing Ni 2+ and chelating ligands (ethylenediaminetetraacetic acid, nitrilotriacetic acid (NTA)) as well as soil fulvic acid. Limited spectral changes are observed for aqueous Ni(II) complexes with monocarboxylates (formate, acetate) and long-chain polycarboxylates (succinate, tricarballylate), where individual donor groups are separated by multiple bridging methylene groups. These spectral changes indicate weak interactions between Ni(II) and carboxylates, and the trends are similar to some earlier reports for crystalline Ni(II)-acetate solids, for which X-ray crystallography studies have indicated monodentate Ni(II)-carboxylate coordination. Nonetheless, electrostatic or outer-sphere coordination cannot be ruled out for these complexes. However, spectral changes observed for short-chain dicarboxylates (oxalate, malonate) and carboxylates that contain an alcohol donor group adjacent to one of the carboxylate groups (lactate, malate, citrate) demonstrate inner-sphere metal coordination by multiple donor groups. XAFS spectral fits of Ni(II) solutions containing soil fulvic acid are consistent with inner-sphere Ni(II) coordination by one or more carboxylate groups, but spectra are noisy and outer-sphere modes of coordination cannot be ruled out. These molecular studies refine our understanding of the interactions between carboxylates and weakly complexing divalent transition metals, such as Ni(II).

Unravelling the surface chemistry of metal oxide nanocrystals, the role of acids and bases.

PubMed

De Roo, Jonathan; Van den Broeck, Freya; De Keukeleere, Katrien; Martins, José C; Van Driessche, Isabel; Hens, Zeger

2014-07-09

We synthesized HfO2 nanocrystals from HfCl4 using a surfactant-free solvothermal process in benzyl alcohol and found that the resulting nanocrystals could be transferred to nonpolar media using a mixture of carboxylic acids and amines. Using solution (1)H NMR, FTIR, and elemental analysis, we studied the details of the transfer reaction and the surface chemistry of the resulting sterically stabilized nanocrystals. As-synthesized nanocrystals are charge-stabilized by protons, with chloride acting as the counterion. Treatment with only carboxylic acids does not lead to any binding of ligands to the HfO2 surface. On the other hand, we find that the addition of amines provides the basic environment in which carboxylic acids can dissociate and replace chloride. This results in stable, aggregate-free dispersions of HfO2 nanocrystals, sterically stabilized by carboxylate ligands. Moreover, titrations with deuterated carboxylic acid show that the charge on the carboxylate ligands is balanced by coadsorbed protons. Hence, opposite from the X-type/nonstoichiometric nanocrystals picture prevailing in literature, one should look at HfO2/carboxylate nanocrystals as systems where carboxylic acids are dissociatively adsorbed to bind to the nanocrystals. Similar results were obtained with ZrO2 NCs. Since proton accommodation on the surface is most likely due to the high Brønsted basicity of oxygen, our model could be a more general picture for the surface chemistry of metal oxide nanocrystals with important consequences on the chemistry of ligand exchange reactions.

Rh(III)-Catalyzed Decarboxylative Coupling of Acrylic Acids with Unsaturated Oxime Esters: Carboxylic Acids Serve as Traceless Activators

PubMed Central

2015-01-01

α,β-Unsaturated carboxylic acids undergo Rh(III)-catalyzed decarboxylative coupling with α,β-unsaturated O-pivaloyl oximes to provide substituted pyridines in good yield. The carboxylic acid, which is removed by decarboxylation, serves as a traceless activating group, giving 5-substituted pyridines with very high levels of regioselectivity. Mechanistic studies rule out a picolinic acid intermediate, and an isolable rhodium complex sheds further light on the reaction mechanism. PMID:24512241

Cognitive Apprenticeship as a Vehicle for Enhancing the Understanding and Functionalization of Organic Chemistry Knowledge

ERIC Educational Resources Information Center

Putica, Katarina; Trivic, Dragica D.

2016-01-01

This paper presents a pedagogical experiment with parallel groups through which the effectiveness of the cognitive apprenticeship model of dealing with the teaching topic "Carboxylic acids and their derivatives" was compared with the traditional approach to the elaboration of this topic. This experiment featured the participation of 241…

The chemistry of aminoguanidine derivatives - preparation, crystal structure, thermal properties, and molecular docking studies of aminoguanidinium salts of several carboxylic acids

NASA Astrophysics Data System (ADS)

Selvakumar, Rajendran; Geib, Steven J.; Muthu Sankar, Aathi; Premkumar, Thathan; Govindarajan, Subbaiah

2015-11-01

The reaction of aminoguanidine bicarbonate (Amg) with oxamic, oxalic, malonic and sulfoacetic acids yielded (AmgH)H2NOC-COO (1), OOC-CONHNHC(NH2)NH2 (2) (AmgH)HOOC-CH2-COO (3) and O3S-CH2-CONHNHC(NH2)NH2 (4), respectively. For the first time, we studied the salt-forming ability of aminoguanidine with several carboxylic acids, such as oxamic, oxalic, malonic and sulphoacetic acids. We also compared the structural and thermal properties of these salts. Oxamic and malonic acids form only mono-aminoguanidinium salts, whereas oxalic acid mainly forms di-aminoguanidinium oxalate. In addition, oxalic acid forms guanylhydrazido-oxalic acid which exists as zwitter ion. Unlike other acids, sulfoacetic acid readily forms only the zwitter ionic salts (2-guanylhydrazido-oxo-methanesulfonic acid) rather than the usual simple salt. This result may be a result of the highly acidic nature of the sulfonic group, which favors acid catalyzed condensation. More significantly, for the first time, the ability guanylhydrazido-oxalic acid (2) and 2-guanylhydrazido-oxo-methanesulfonic acid (4) to inhibit human butyrylcholinesterase (human BChE) receptor has been studied with a molecular docking approach. The binding of the compounds to human BChE was examined as it is crucial to understanding the biological significance of aminoguanidine derivatives. The compounds were identified and characterized by analytical, FT-IR spectroscopic and thermal studies. Furthermore, the structures of compounds 1, 2 and 4 were confirmed by single X-ray diffraction studies. Compounds 1 and 2 crystallized in a monoclinic crystal system with P21/c and Cc space groups, respectively, whereas compound 4 crystalized in an orthorhombic system with a Pbca space group. All the compounds (1-4) underwent endo- followed by exothermic decomposition in the temperature range from 130 to 600 °C to yield gaseous products.

Transition-metal-free visible-light photoredox catalysis at room-temperature for decarboxylative fluorination of aliphatic carboxylic acids by organic dyes.

PubMed

Wu, Xinxin; Meng, Chunna; Yuan, Xiaoqian; Jia, Xiaotong; Qian, Xuhong; Ye, Jinxing

2015-07-28

We report herein an efficient, general and green method for decarboxylative fluorination of aliphatic carboxylic acids. By using a transition-metal-free, organocatalytic photoredox system, the reaction of various aliphatic carboxylic acids with the Selectfluor reagent afforded the corresponding alkyl fluorides in satisfactory yields under visible light irradiation at room temperature.

Anaerobic Fermentation for Production of Carboxylic Acids as Bulk Chemicals from Renewable Biomass.

PubMed

Wang, Jufang; Lin, Meng; Xu, Mengmeng; Yang, Shang-Tian

Biomass represents an abundant carbon-neutral renewable resource which can be converted to bulk chemicals to replace petrochemicals. Carboxylic acids have wide applications in the chemical, food, and pharmaceutical industries. This chapter provides an overview of recent advances and challenges in the industrial production of various types of carboxylic acids, including short-chain fatty acids (acetic, propionic, butyric), hydroxy acids (lactic, 3-hydroxypropionic), dicarboxylic acids (succinic, malic, fumaric, itaconic, adipic, muconic, glucaric), and others (acrylic, citric, gluconic, pyruvic) by anaerobic fermentation. For economic production of these carboxylic acids as bulk chemicals, the fermentation process must have a sufficiently high product titer, productivity and yield, and low impurity acid byproducts to compete with their petrochemical counterparts. System metabolic engineering offers the tools needed to develop novel strains that can meet these process requirements for converting biomass feedstock to the desirable product.

Regioselective Ni-Catalyzed Carboxylation of Allylic and Propargylic Alcohols with Carbon Dioxide.

PubMed

Chen, Yue-Gang; Shuai, Bin; Ma, Cong; Zhang, Xiu-Jie; Fang, Ping; Mei, Tian-Sheng

2017-06-02

An efficient Ni-catalyzed reductive carboxylation of allylic alcohols with CO 2 has been successfully developed, providing linear β,γ-unsaturated carboxylic acids as the sole regioisomer with generally high E/Z stereoselectivity. In addition, the carboxylic acids can be generated from propargylic alcohols via hydrogenation to give allylic alcohol intermediates, followed by carboxylation. A preliminary mechanistic investigation suggests that the hydrogenation step is made possible by a Ni hydride intermediate produced by a hydrogen atom transfer from water.

Enantiomeric and Isotopic Analysis of Sugar Derivatives in Carbonaceous Meteorites

NASA Technical Reports Server (NTRS)

Cooper, George; Asiyo, Cynthia; Turk, Kendra; DeVincenzi, Donald (Technical Monitor)

2002-01-01

Several classes of organic compounds are found in carbonaceous meteorites including amino acids, carboxylic acids, hydroxy acids, purines, and pyrimidines. Such compounds are thought to have been delivered to the early Earth in asteroids and comets and may have played a role in the origin of life. Likewise, sugar derivatives are critical to all known lifeforms. Recent analyses of the Murchison and Murray carbonaceous meteorites revealed a diverse suite of such derivatives, i.e., sugar alcohols, and sugar acids. This presentation will focus primarily on the analysis of individual sugar acids - their enantiomeric and isotopic composition. Analysis of these compounds may reveal the nature of past (or present) meteoritic sugars themselves. For example, if parent sugars decomposed (by well-known mechanisms) to give the present acids, were their enantiomeric ratios preserved? Combined with other evidence, the enantiomeric composition of such compounds as glyceric acid and (especially) rare acids may help to answer such questions. C-13 and D isotope analysis of meteoritic sugar alcohols (glycerol, threitol, ribitol, etc.) as a group revealed that they were indigenous to the meteorite. Preliminary C-13 analysis of glyceric acid shows that it is also extraterrestrial.

Signal enhancement of carboxylic acids by inclusion with β-cyclodextrin in negative high-voltage-assisted laser desorption ionization mass spectrometry.

PubMed

Ren, Xinxin; Liu, Jia; Zhang, Chengsen; Sun, Jiamu; Luo, Hai

2014-01-15

It is difficult to directly analyze carboxylic acids in complex mixtures by ambient high-voltage-assisted laser desorption ionization mass spectrometry (HALDI-MS) in negative ion mode due to the low ionization efficiency of carboxylic acids. A method for the rapid detection of carboxylic acids in negative HALDI-MS has been developed based on their inclusion with β-cyclodextrin (β-CD). The negative HALDI-MS signal-to-noise ratios (S/Ns) of aliphatic, aromatic and hetero atom-containing carboxylic acids can all be significantly improved by forming 1:1 complexes with β-CD. These complexes are mainly formed by specific inclusion interactions which are verified by their collision-induced dissociation behaviors in comparison with that of their corresponding maltoheptaose complexes. A HALDI-MS/MS method has been successfully developed for the detection of α-lipoic acid in complex cosmetics and ibuprofen in a viscous drug suspension. The negative HALDI-MS S/Ns of carboxylic acids can be improved up to 30 times via forming non-covalent complexes with β-CD. The developed method shows the advantages of being rapid and simple, and is promising for rapid detection of active ingredients in complex samples or fast screening of drugs and cosmetics. Copyright © 2013 John Wiley & Sons, Ltd.

Artificial photosynthesis of. beta. -ketocarboxylic acids from carbon dioxide and ketones via enolate complexes of aluminum porphyrin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hirai, Yasuhiro; Aida, Takuzo; Inoue, Shohei

1989-04-12

Photochemical fixation of carbon dioxide is of much interest in connection with biological photosynthesis by green plants as well as from the viewpoint of carbon resource utilization. One of the important steps in the assimilation of carbon dioxide is the carboxylation of a carbonyl compound into ketocarboxylic acid, where the reaction proceeds via an enolate species as reactive intermediate. For example, in four carbon (C{sub 4}) pathway and Crassulacean acid metabolism (CAM) processes, pyruvate is converted with the aid of ATP into phosphoenolpyruvate, which is subsequently carboxylated to give oxaloacetate by the action of pyruvate carboxylase. In relation to thismore » interesting biological process, some artificial systems have been exploited for the synthesis of {beta}-ketocarboxylic acid derivatives from carbon dioxide and ketones using nucleophiles such as metal carbonates, thiazolates, phenolates, alkoxides, and strong organic as well as inorganic basis, which promote the enolization of ketones in the intermediate step. We wish to report here a novel, visible light-induced fixation of carbon dioxide with the enolate complex of aluminum porphyrin, giving {beta}-ketocarboxylic acid under mild conditions.« less

Catalytic transformation of functionalized carboxylic acids using multifunctional rhenium complexes.

PubMed

Naruto, Masayuki; Agrawal, Santosh; Toda, Katsuaki; Saito, Susumu

2017-06-13

Carboxylic acids (CAs) are one of the most ubiquitous and important chemical feedstocks available from biorenewable resources, CO 2 , and the petrochemical industry. Unfortunately, chemoselective catalytic transformations of CH n CO 2 H (n = 1-3) groups into other functionalities remain a significant challenge. Herein, we report rhenium V complexes as extremely effective precatalysts for this purpose. Compared to previously reported heterogeneous and homogeneous catalysts derived from high- or low-valent metals, the present method involves a α-C-H bond functionalization, a hydrogenation, and a hydrogenolysis, which affords functionalized alcohols with a wide substrate scope and high chemoselectivity under relatively mild reaction conditions. The results represent an important step toward a paradigm shift from 'low-valent' to 'high-valent' metal complexes by exploring a new portfolio of selective functional group transformations of highly oxygenated organic substrates, as well as toward the exploitation of CAs as a valuable biorenewable feedstock.

Structure-based design of novel quinoxaline-2-carboxylic acids and analogues as Pim-1 inhibitors.

PubMed

Oyallon, Bruno; Brachet-Botineau, Marie; Logé, Cédric; Bonnet, Pascal; Souab, Mohamed; Robert, Thomas; Ruchaud, Sandrine; Bach, Stéphane; Berthelot, Pascal; Gouilleux, Fabrice; Viaud-Massuard, Marie-Claude; Denevault-Sabourin, Caroline

2018-05-11

We identified a new series of quinoxaline-2-carboxylic acid derivatives, targeting the human proviral integration site for Moloney murine leukemia virus-1 (HsPim-1) kinase. Seventeen analogues were synthesized providing useful insight into structure-activity relationships studied. Docking studies realized in the ATP pocket of HsPim-1 are consistent with an unclassical binding mode of these inhibitors. The lead compound 1 was able to block HsPim-1 enzymatic activity at nanomolar concentrations (IC 50 of 74 nM), with a good selectivity profile against a panel of mammalian protein kinases. In vitro studies on the human chronic myeloid leukemia cell line KU812 showed an antitumor activity at micromolar concentrations. As a result, compound 1 represents a promising lead for the design of novel anticancer targeted therapies. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Influence of Functional Groups on the Viscosity of Organic Aerosol.

PubMed

Rothfuss, Nicholas E; Petters, Markus D

2017-01-03

Organic aerosols can exist in highly viscous or glassy phase states. A viscosity database for organic compounds with atmospherically relevant functional groups is compiled and analyzed to quantify the influence of number and location of functional groups on viscosity. For weakly functionalized compounds the trend in viscosity sensitivity to functional group addition is carboxylic acid (COOH) ≈ hydroxyl (OH) > nitrate (ONO 2 ) > carbonyl (CO) ≈ ester (COO) > methylene (CH 2 ). Sensitivities to group addition increase with greater levels of prior functionalization and decreasing temperature. For carboxylic acids a sharp increase in sensitivity is likely present already at the second addition at room temperature. Ring structures increase viscosity relative to linear structures. Sensitivities are correlated with analogously derived sensitivities of vapor pressure reduction. This may be exploited in the future to predict viscosity in numerical models by piggybacking on schemes that track the evolution of organic aerosol volatility with age.

[A new eremophilane derivative from Senecio dianthus].

PubMed

Han, He-Dong; Hu, Hai-Qing; Li, Yan; Wang, Xiao-Ling

2013-10-01

A new eremophilane derivative, 4,5,11-trimethyl-9( 10), 7 ( 11) -eremophiladien-8-keto-12-carboxylic acid-beta-D-glucopyranoside( which named dianthuside A) 1 and four known compounds, 5,7,4'-trihydroxy-flavonone-3-0-beta-D-glucoside (2), quercetin-3-0-beta-D-glucoside(3) ,hyperin(4) and rutin(5) have been isolated from the aerial part of Senecio dianthus. Their structures were elucidated by physicochemical properties and spectroscopic data analysis. Compounds 2, 4 and 5 were isolated from this plant for the first time.

Hole and electron extraction layers based on graphene oxide derivatives for high-performance bulk heterojunction solar cells.

PubMed

Liu, Jun; Xue, Yuhua; Gao, Yunxiang; Yu, Dingshan; Durstock, Michael; Dai, Liming

2012-05-02

By charge neutralization of carboxylic acid groups in graphene oxide (GO) with Cs(2)CO(3) to afford Cesium-neutralized GO (GO-Cs), GO derivatives with appropriate modification are used as both hole- and electron-extraction layers for bulk heterojunction (BHJ) solar cells. The normal and inverted devices based on GO hole- and GO-Cs electron-extraction layers both outperform the corresponding standard BHJ solar cells. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Conformational characterization of the 1-aminocyclobutane-1-carboxylic acid residue in model peptides.

PubMed

Gatos, M; Formaggio, F; Crisma, M; Toniolo, C; Bonora, G M; Benedetti, Z; Di Blasio, B; Iacovino, R; Santini, A; Saviano, M; Kamphuis, J

1997-01-01

A series of N- and C-protected, monodispersed homo-oligopeptides (to the dodecamer level) from the small-ring alicyclic C alpha, alpha-dialkylated glycine 1-aminocyclobutane-1-carboxylic acid (Ac4c) and two Ala/Ac4c tripeptides were synthesized by solution methods and fully characterized. The conformational preferences of all the model peptides were determined in deuterochloroform solution by FT-IR absorption and 1H-NMR. The molecular structures of the amino acid derivatives Z-Ac4c-OH and Z2-Ac4c-OH, the tripeptides Z-(Ac4c)3-OtBu, Z-Ac4c-(L-Ala)2-OMe and Z-L-Ala-Ac4c-L-Ala-OMe, and the tetrapeptide Z-(Ac4c)4-OtBu were determined in the crystal state by X-ray diffraction. The average geometry of the cyclobutyl moiety of the Ac4c residue was assessed and the tau(N-C alpha-C') bond angle was found to be significantly expanded from the regular tetrahedral value. The conformational data are strongly in favour of the conclusion that the Ac4c residue is an effective beta-turn and helix former. A comparison with the structural propensities of alpha-aminoisobutyric acid, the prototype of C alpha, alpha-dialkylated glycines, and the other extensively investigated members of the family of 1-aminocycloalkane-1-carboxylic acids (Acnc, with n = 3, 5-8) is made and the implications for the use of the Ac4c residue in conformationally constrained peptide analogues are briefly examined.

DETERMINATION OF CARBOXYLIC ACIDS BY ION-EXCLUSION CHROMATOGRAPHY WITH NON-SUPPRESSED CONDUCTIVITY AND OPTICAL DETECTORS

EPA Science Inventory

Determination of carboxylic acids using non-suppressed conductivity and UV detections is described. The background conductance of 1-octanesulfonic acid, hexane sulfonic acid and sulfuric acid at varying concentrations was determined. Using 0.2 mM 1-octanesulfonic acid as a mobile...

A comparative guide to controlled hydrophobization of cellulose nanocrystals via surface esterification

Treesearch

Shane X. Peng; Huibin Chang; Satish Kumar; Robert J. Moon; Jeffrey P. Youngblood

2016-01-01

Surface esterification methods of cellulose nanocrystals (CNC) using acid anhydrides, acid chlorides, acid catalyzed carboxylic acids, and 101-carbonyldiimidazole (CDI) activated carboxylic acids were evaluated with acetyl-, hexanoyl-, dodecanoyl-, oleoyl-, and methacryloyl-functionalization. Their grafting efficiency was investigated using Fouriertransform infrared...

Thermal transformation of bioactive caffeic acid on fumed silica seen by UV-Vis spectroscopy, thermogravimetric analysis, temperature programmed desorption mass spectrometry and quantum chemical methods.

PubMed

Kulik, Tetiana V; Lipkovska, Natalia O; Barvinchenko, Valentyna M; Palyanytsya, Borys B; Kazakova, Olga A; Dudik, Olesia O; Menyhárd, Alfréd; László, Krisztina

2016-05-15

Thermochemical studies of hydroxycinnamic acid derivatives and their surface complexes are important for the pharmaceutical industry, medicine and for the development of technologies of heterogeneous biomass pyrolysis. In this study, structural and thermal transformations of caffeic acid complexes on silica surfaces were studied by UV-Vis spectroscopy, thermogravimetric analysis, temperature programmed desorption mass spectrometry (TPD MS) and quantum chemical methods. Two types of caffeic acid surface complexes are found to form through phenolic or carboxyl groups. The kinetic parameters of the chemical reactions of caffeic acid on silica surface are calculated. The mechanisms of thermal transformations of the caffeic chemisorbed surface complexes are proposed. Thermal decomposition of caffeic acid complex chemisorbed through grafted ester group proceeds via three parallel reactions, producing ketene, vinyl and acetylene derivatives of 1,2-dihydroxybenzene. Immobilization of phenolic acids on the silica surface improves greatly their thermal stability. Copyright © 2016 Elsevier Inc. All rights reserved.

Citric-Acid-Derived Photo-cross-Linked Biodegradable Elastomers

PubMed Central

Gyawali, Dipendra; Tran, Richard T.; Guleserian, Kristine J.; Tang, Liping; Yang, Jian

2010-01-01

Citric-acid-derived thermally cross-linked biodegradable elastomers (CABEs) have recently received significant attention in various biomedical applications, including tissue-engineering orthopedic devices, bioimaging and implant coatings. However, citric-acid-derived photo-cross-linked biodegradable elastomers are rarely reported. Herein, we report a novel photo-cross-linked biodegradable elastomer, referred to as poly(octamethylene maleate citrate) (POMC), which preserves pendant hydroxyl and carboxylic functionalities after cross-linking for the potential conjugation of biologically active molecules. POMC is a low-molecular-mass pre-polymer with a molecular mass average between 701 and 1291 Da. POMC networks are soft and elastic with an initial modulus of 0.07 to 1.3 MPa and an elongation at break between 38 and 382%. FT-IR–ATR results confirmed the successful surface immobilization of type-I collagen onto POMC films, which enhanced in vitro cellular attachment and proliferation. Photo-polymerized POMC films implanted subcutaneously into Sprague–Dawley rats demonstrated minimal in vivo inflammatory responses. The development of POMC enriches the family of citric-acid-derived biodegradable elastomers and expands the available biodegradable polymers for versatile needs in biomedical applications. PMID:20557687

Complex formation of vanadium(V) with resorcylalhydrazides of carboxylic acids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dudarev, V.I.; Dolgorev, V.A.; Volkov, A.N.

1986-08-01

In this work, a previous investigation of hydrazine derivatives as analytical reagents for vanadium(V) was continued. The authors studied arylalhydrazones -- derivatives of resorcylalhydrazides of anisic (RHASA), anthranilic (RHANA), and benzoic (RHBA) acids. The reagents presented differ from those studied previously by the presence of a second hydroxy group in the para-position of the benzene ring -the resorcinol fragment -- and substituents in the benzoin fragment. Such changes made it possible to increase the solubility of the reagents in aqueous medium and to estimate the change in the main spectrophotometric parameters of the analytical reaction. A rapid method was developedmore » for the determination of vanadium in steels with the resorcylalhydrazide of anthranilic acid. The minimum determinable vanadium content is 0.18 micrograms/ml.« less

Effect of alkali metal ions on the pyrrole and pyridine π-electron systems in pyrrole-2-carboxylate and pyridine-2-carboxylate molecules: FT-IR, FT-Raman, NMR and theoretical studies

NASA Astrophysics Data System (ADS)

Świderski, G.; Wojtulewski, S.; Kalinowska, M.; Świsłocka, R.; Lewandowski, W.

2011-05-01

The FT-IR, FT-Raman and 1H and 13C NMR spectra of pyrrole-2-carboxylic acid (PCA) and lithium, sodium, potassium, rubidium and caesium pyrrole-2-carboxylates were recorded, assigned and compared in the Li → Na → K → Rb → Cs salt series. The effect of alkali metal ions on the electronic system of ligands was discussed. The obtained results were compared with previously reported ones for pyridine-2-carboxylic acid and alkali metal pyridine-2-carboxylates. Calculations for pyrrole-2-carboxylic acid and Li, Na, K pyrrole-2-carboxylates in B3LYP/6-311++G ** level and Møller-Plesset method in MP2/6-311++G ** level were made. Bond lengths, angles and dipole moments as well as aromaticity indices (HOMA, EN, GEO, I 6) for the optimized structures of pyrrole-2-carboxylic acid (PCA) and lithium, sodium, potassium pyrrole-2-carboxylates were also calculated. The degree of perturbation of the aromatic system of ligand under the influence of metals in the Li → Cs series was investigated with the use of statistical methods (linear correlation), calculated aromaticity indices and Mulliken, NBO and ChelpG population analysis method. Additionally, the Bader theory (AIM) was applied to setting the characteristic of the bond critical points what confirmed the influence of alkali metals on the pyrrole ring.

Use of a polystyrene-divinylbenzene-based weakly acidic cation-exchange resin column and propionic acid as an eluent in ion-exclusion/adsorption chromatography of aliphatic carboxylic acids and ethanol in food samples.

PubMed

Mori, Masanobu; Hironaga, Takahiro; Kajiwara, Hiroe; Nakatani, Nobutake; Kozaki, Daisuke; Itabashi, Hideyuki; Tanaka, Kazuhiko

2011-01-01

We developed an ion-exclusion/adsorption chromatography (IEAC) method employing a polystyrene-divinylbenzene-based weakly acidic cation-exchange resin (PS-WCX) column with propionic acid as the eluent for the simultaneous determination of multivalent aliphatic carboxylic acids and ethanol in food samples. The PS-WCX column well resolved mono-, di-, and trivalent carboxylic acids in the acidic eluent. Propionic acid as the eluent gave a higher signal-to-noise ratio, and enabled sensitive conductimetric detection of analyte acids. We found the optimal separation condition to be the combination of a PS-WCX column and 20-mM propionic acid. Practical applicability of the developed method was confirmed by using a short precolumn with a strongly acidic cation-exchange resin in the H(+)-form connected before the separation column; this was to remove cations from food samples by converting them to hydrogen ions. Consequently, common carboxylic acids and ethanol in beer, wine, and soy sauce were successfully separated by the developed method.

Amino Acids, Aromatic Compounds, and Carboxylic Acids: How Did They Get Their Common Names?

ERIC Educational Resources Information Center

Leung, Sam H.

2000-01-01

Surveys the roots of the common names of organic compounds most likely to be encountered by undergraduate organic chemistry students. Includes information for 19 amino acids, 17 aromatic compounds, and 21 carboxylic acids. (WRM)

The effect of carboxylic acids on the oxidation of coated iron oxide nanoparticles

NASA Astrophysics Data System (ADS)

Lengyel, Attila; Tolnai, Gyula; Klencsár, Zoltán; Garg, Vijayendra Kumar; de Oliveira, Aderbal Carlos; Herojit Singh, L.; Homonnay, Zoltán; Szalay, Roland; Németh, Péter; Szabolcs, Bálint; Ristic, Mira; Music, Svetozar; Kuzmann, Ernő

2018-05-01

57Fe Mössbauer spectroscopy, XRD, and TEM were used to investigate the effect of mandelic- and salicylic acid coatings on the iron oxide nanoparticles. These two carboxylic acids have similar molecules size and stoichiometry, but different structure and acidity. Significant differences were observed between the Mössbauer spectra of samples coated with mandelic acid and salicylic acid. These results indicate that the occurrence of iron microenvironments in the mandelic- and salicylic acid-coated iron oxide nanoparticles is different. The results can be interpreted in terms of the influence of the acidity of carboxylic acids on the formation, core/shell structure, and oxidation of coated iron oxide nanocomposites.

Elongated and substituted triazine-based tricarboxylic acid linkers for MOFs.

PubMed

Klinkebiel, Arne; Beyer, Ole; Malawko, Barbara; Lüning, Ulrich

2016-01-01

New triazine-based tricarboxylic acid linkers were prepared as elongated relatives of triazinetribenzoic acid (TATB). Additionally, functional groups (NO 2 , NH 2 , OMe, OH) were introduced for potential post-synthetic modification (PSM) of MOFs. Functionalized tris(4-bromoaryl)triazine "cores" ( 3a , 3b ) were obtained by unsymmetric trimerization mixing one equivalent of an acid chloride (OMe or NO 2 substituted) with two equivalents of an unsubstituted nitrile. Triple Suzuki coupling of the cores 3 with suitable phenyl- and biphenylboronic acid derivatives provided elongated tricarboxylic acid linkers as carboxylic acids 17 and 20 or their esters 16 and 19 . Reduction of the nitro group and cleavage of the methoxy group gave the respective amino and hydroxy-substituted triazine linkers.

Elongated and substituted triazine-based tricarboxylic acid linkers for MOFs

PubMed Central

Klinkebiel, Arne; Beyer, Ole; Malawko, Barbara

2016-01-01

New triazine-based tricarboxylic acid linkers were prepared as elongated relatives of triazinetribenzoic acid (TATB). Additionally, functional groups (NO2, NH2, OMe, OH) were introduced for potential post-synthetic modification (PSM) of MOFs. Functionalized tris(4-bromoaryl)triazine “cores” (3a,3b) were obtained by unsymmetric trimerization mixing one equivalent of an acid chloride (OMe or NO2 substituted) with two equivalents of an unsubstituted nitrile. Triple Suzuki coupling of the cores 3 with suitable phenyl- and biphenylboronic acid derivatives provided elongated tricarboxylic acid linkers as carboxylic acids 17 and 20 or their esters 16 and 19. Reduction of the nitro group and cleavage of the methoxy group gave the respective amino and hydroxy-substituted triazine linkers. PMID:28144293

Synthesis and characterization of silver nanoparticles from (bis)alkylamine silver carboxylate precursors.

PubMed

Uznanski, Pawel; Zakrzewska, Joanna; Favier, Frederic; Kazmierski, Slawomir; Bryszewska, Ewa

2017-01-01

A comparative study of amine and silver carboxylate adducts [R 1 COOAg-2(R 2 NH 2 )] (R 1  = 1, 7, 11; R 2  = 8, 12) as a key intermediate in NPs synthesis is carried out via differential scanning calorimetry, solid-state FT-infrared spectroscopy, 13 C CP MAS NMR, powder X-ray diffraction and X-ray photoelectron spectroscopy, and various solution NMR spectroscopies ( 1 H and 13 C NMR, pulsed field gradient spin-echo NMR, and ROESY). It is proposed that carboxyl moieties in the presence of amine ligands are bound to silver ions via chelating bidentate type of coordination as opposed to bridging bidentate coordination of pure silver carboxylates resulting from the formation of dimeric units. All complexes are packed as lamellar bilayer structures. Silver carboxylate/amine complexes show one first-order melting transition. The evidence presented in this study shows that phase behavior of monovalent metal carboxylates are controlled, mainly, by head group bonding. In solution, insoluble silver salt is stabilized by amine molecules which exist in dynamic equilibrium. Using (bis)amine-silver carboxylate complex as precursor, silver nanoparticles were fabricated. During high-temperature thermolysis, the (bis)amine-carboxylate adduct decomposes to produce silver nanoparticles of small size. NPs are stabilized by strongly interacting carboxylate and trace amounts of amine derived from the silver precursor interacting with carboxylic acid. A corresponding aliphatic amide obtained from silver precursor at high-temperature reaction conditions is not taking part in the stabilization. Combining NMR techniques with FTIR, it was possible to follow an original stabilization mechanism. Graphical abstractThe synthesis of a series (bis)alkylamine silver(I) carboxylate complexes in nonpolar solvents were carried out and fully characterized both in the solid and solution. Carboxyl moieties in the presence of amine ligands are bound to silver ions via chelating bidentate type of coordination. The complexes form layered structures which thermally decompose forming nanoparticles stabilized only by aliphatic carboxylates.

Design and Synthesis of Human ABCB1 (P-Glycoprotein) Inhibitors by Peptide Coupling of Diverse Chemical Scaffolds on Carboxyl and Amino Termini of (S)-Valine-Derived Thiazole Amino Acid

PubMed Central

2015-01-01

P-glycoprotein (P-gp) serves as a therapeutic target for the development of multidrug resistance reversal agents. In this study, we synthesized 21 novel compounds by peptide coupling at corresponding carboxyl and amino termini of (S)-valine-based bis-thiazole and monothiazole derivatives with diverse chemical scaffolds. Using calcein-AM efflux assay, we identified compound 28 (IC50 = 1.0 μM) carrying 3,4,5-trimethoxybenzoyl and 2-aminobenzophenone groups, respectively, at the amino and carboxyl termini of the monothiazole zwitter-ion. Compound 28 inhibited the photolabeling of P-gp with [125I]-iodoarylazidoprazosin with IC50 = 0.75 μM and stimulated the basal ATP hydrolysis of P-gp in a concentration-dependent manner (EC50 ATPase = 0.027 μM). Compound 28 at 3 μM reduced resistance in cytotoxicity assay to paclitaxel in P-gp-expressing SW620/Ad300 and HEK/ABCB1 cell lines. Biochemical and docking studies showed site-1 to be the preferable binding site for 28 within the drug-binding pocket of human P-gp. PMID:24773054

Synthesis of the 1-Monoester of 2-Ketoalkanedioic Acids, e.g., Octyl α-Ketoglutarate

PubMed Central

Jung, Michael E.; Deng, Gang

2012-01-01

Oxidative cleavage of cycloalkene-1-carboxylates, made from the corresponding carboxylic acids, and subsequent oxidation of the resulting ketoaldehyde afforded the important 1-monoesters of 2-ketoalkanedioic acids. Thus ozonolysis of octyl cyclobutene-1-carboxylate followed by sodium chlorite oxidation afforded the 1-monooctyl 2-ketoglutarate. This is a cell-permeable prodrug form of α-ketoglutarate, an important intermediate in the tricarboxylic acid (TCA, Krebs) cycle and a promising therapeutic agent in its own right. PMID:23163977

1-Aminocyclopentane-1,2,4-tricarboxylic acids screening on glutamatergic and serotonergic systems.

PubMed

Gelmi, Maria Luisa; Caputo, Francesco; Clerici, Francesca; Pellegrino, Sara; Giannaccini, Gino; Betti, Laura; Fabbrini, Laura; Schmid, Lara; Palego, Lionella; Lucacchini, Antonio

2007-12-15

Enantiopure constrained 1-aminocyclopentane-1,2,4-tricarboxylic acids containing the glutamic acid skeleton were prepared as two diastereomers characterized by having the carboxylic groups in position two and four cis-oriented to each other and trans with respect to 1-carboxylic group and all cis-oriented carboxylic groups, respectively. A biochemical screening of activity of the above amino acids was investigated on glutamate and 5-HT receptors to find a possible metabotropic agonist, acting on the serotoninergic system.

Carboxylic acid isosteres improve the activity of ring-fused 2-pyridones that inhibit pilus biogenesis in E. coli

PubMed Central

Åberg, Veronica; Das, Pralay; Chorell, Erik; Hedenström, Mattias; Pinkner, Jerome S.; Hultgren, Scott J.; Almqvist, Fredrik

2009-01-01

Ring-fused 2-pyridones, termed pilicides, are small synthetic compounds that inhibit pilus assembly in uropathogenic E. coli. Their biological activity is clearly dependent upon a carboxylic acid functionality. Here we present the synthesis and biological evaluation of carboxylic acid isosteres, including e.g. tetrazoles, acyl sulfonamides and hydroxamic acids, of two lead 2-pyridones. Two independent biological evaluations show that acyl sulfonamides and tetrazoles significantly improve pilicide activity against uropathogenic E. coli. PMID:18499455

Wet spinning of solid polyamic acid fibers

NASA Technical Reports Server (NTRS)

Dorogy, William E., Jr. (Inventor); St.clair, Anne K. (Inventor)

1991-01-01

The invention is a process for the production of solid aromatic polyamic acid and polyimide fibers from a wet gel or coagulation bath wet gel using N,N-dimethylacetamide (DMAc) solutions of the polyamic acid derived from aromatic dianhydrides such as 3,3',4,4' benzophenonetetra carboxylic dianhydride (BTDA) and aromatic diamines such as 4,4'-oxydianiline (4,4'-ODA). By utilizing the relationship among coagulation medium and concentration, resin inherent viscosity, resin percent solids, filament diameter, and fiber void content, it is possible to make improved polyamic acid fibers. Solid polyimide fibers, obtained by the thermal cyclization of the polyamic acid precursor, have increased tensile properties compared to fibers containing macropores from the same resin system.

RNA interference of 1-aminocyclopropane-1-carboxylic acid oxidase (ACO1 and ACO2) genes expression prolongs the shelf life of Eksotika (Carica papaya L.) papaya fruit.

PubMed

Sekeli, Rogayah; Abdullah, Janna Ong; Namasivayam, Parameswari; Muda, Pauziah; Abu Bakar, Umi Kalsom; Yeong, Wee Chien; Pillai, Vilasini

2014-06-19

The purpose of this study was to evaluate the effectiveness of using RNA interference in down regulating the expression of 1-aminocyclopropane-1-carboxylic acid oxidase gene in Eksotika papaya. One-month old embryogenic calli were separately transformed with Agrobacterium strain LBA 4404 harbouring the three different RNAi pOpOff2 constructs bearing the 1-aminocyclopropane-1-carboxylic acid oxidase gene. A total of 176 putative transformed lines were produced from 15,000 calli transformed, selected, then regenerated on medium supplemented with kanamycin. Integration and expression of the targeted gene in putatively transformed lines were verified by PCR and real-time RT-PCR. Confined field evaluation of a total of 31 putative transgenic lines planted showed a knockdown expression of the targeted ACO1 and ACO2 genes in 13 lines, which required more than 8 days to achieve the full yellow colour (Index 6). Fruits harvested from lines pRNAiACO2 L2-9 and pRNAiACO1 L2 exhibited about 20 and 14 days extended post-harvest shelf life to reach Index 6, respectively. The total soluble solids contents of the fruits ranged from 11 to 14° Brix, a range similar to fruits from non-transformed, wild type seed-derived plants.

Lead optimization of a pyridine-carboxamide series as DGAT-1 inhibitors.

PubMed

Ting, Pauline C; Lee, Joe F; Zorn, Nicolas; Kim, Hyunjin M; Aslanian, Robert G; Lin, Mingxiang; Smith, Michelle; Walker, Scott S; Cook, John; Van Heek, Margaret; Lachowicz, Jean

2013-02-15

The structure-activity relationship studies of a novel series of carboxylic acid derivatives of pyridine-carboxamides as DGAT-1 inhibitors is described. The optimization of the initial lead compound 6 based on in vitro and in vivo activity led to the discovery of key compounds 10j and 17h. Copyright © 2013 Elsevier Ltd. All rights reserved.

Co(II) and Cd(II) Complexes Derived from Heterocyclic Schiff-Bases: Synthesis, Structural Characterisation, and Biological Activity

PubMed Central

Ahmed, Riyadh M.; Yousif, Enaam I.; Al-Jeboori, Mohamad J.

2013-01-01

New monomeric cobalt and cadmium complexes with Schiff-bases, namely, N′-[(E)-(3-hydroxy-4-methoxyphenyl)methylidene]furan-2-carbohydrazide (L1) and N′-[(E)-(3-hydroxy-4-methoxyphenyl)methylidene]thiophene-2-carbohydrazide (L2) are reported. Schiff-base ligands L1 and L2 were derived from condensation of 3-hydroxy-4-methoxybenzaldehyde (iso-vanillin) with furan-2-carboxylic acid hydrazide and thiophene-2-carboxylic acid hydrazide, respectively. Complexes of the general formula [M(L)2]Cl2 (where M = Co(II) or Cd(II), L = L1 or L2) have been obtained from the reaction of the corresponding metal chloride with the ligands. The ligands and their metal complexes were characterised by spectroscopic methods (FTIR, UV-Vis, 1H, and 13C NMR spectra), elemental analysis, metal content, magnetic measurement, and conductance. These studies revealed the formation of four-coordinate complexes in which the geometry about metal ion is tetrahedral. Biological activity of the ligands and their metal complexes against gram positive bacterial strain Bacillus (G+) and gram negative bacteria Pseudomonas (G−) revealed that the metal complexes become less resistive to the microbial activities as compared to the free ligands. PMID:24027449

Immobilization-stabilization of proteins on nanofibrillated cellulose derivatives and their bioactive film formation.

PubMed

Arola, Suvi; Tammelin, Tekla; Setälä, Harri; Tullila, Antti; Linder, Markus B

2012-03-12

In a number of different applications for enzymes and specific binding proteins a key technology is the immobilization of these proteins to different types of supports. In this work we describe a concept for protein immobilization that is based on nanofibrillated cellulose (NFC). NFC is a form of cellulose where fibers have been disintegrated into fibrils that are only a few nanometers in diameter and have a very large aspect ratio. Proteins were conjugated through three different strategies using amine, epoxy, and carboxylic acid functionalized NFC. The conjugation chemistries were chosen according to the reactive groups on the NFC derivatives; epoxy amination, heterobifunctional modification of amino groups, and EDC/s-NHS activation of carboxylic acid groups. The conjugation reactions were performed in solution and immobilization was performed by spin coating the protein-NCF conjugates. The structure of NFC was shown to be advantageous for both protein performance and stability. The use of NFC allows all covalent chemistry to be performed in solution, while the immobilization is achieved by a simple spin coating or spreading of the protein-NFC conjugates on a support. This allows more scalable methods and better control of conditions compared to the traditional methods that depend on surface reactions.

Safety Assessment of Acyl Glucuronides-A Simplified Paradigm.

PubMed

Smith, Dennis A; Hammond, Timothy; Baillie, Thomas A

2018-06-01

While simple O - (ether-linked) and N -glucuronide drug conjugates generally are unreactive and considered benign from a safety perspective, the acyl glucuronides that derive from metabolism of carboxylic acid-containing xenobiotics can exhibit a degree of chemical reactivity that is dependent upon their molecular structure. As a result, concerns have arisen over the safety of acyl glucuronides as a class, several members of which have been implicated in the toxicity of their respective parent drugs. However, direct evidence in support of these claims remains sparse, and due to frequently encountered species differences in the systemic exposure to acyl glucuronides (both of the parent drug and oxidized derivatives thereof), coupled with their instability in aqueous media and potential to undergo chemical rearrangement (acyl migration), qualification of these conjugates by traditional safety assessment methods can be very challenging. In this Commentary, we discuss alternative (non-acyl glucuronide) mechanisms by which carboxylic acids may cause serious adverse reactions, and propose a novel, practical approach to compare systemic exposure to acyl glucuronide metabolites in humans to that in animal species used in preclinical safety assessment based on relative estimates of the total body burden of these circulating conjugates. Copyright © 2018 by The American Society for Pharmacology and Experimental Therapeutics.

Solvent-Free Esterification of Carboxylic Acids Using Supported Iron Oxide Nanoparticles as an Efficient and Recoverable Catalyst

PubMed Central

Rajabi, Fatemeh; Abdollahi, Mohammad; Luque, Rafael

2016-01-01

Supported iron oxide nanoparticles on mesoporous materials (FeNP@SBA-15) have been successfully utilized in the esterification of a variety carboxylic acids including aromatic, aliphatic, and long-chain carboxylic acids under convenient reaction conditions. The supported catalyst could be easily recovered after reaction completion and reused several times without any loss in activity after up to 10 runs. PMID:28773685

Decarboxylative Trifluoromethylation of Aliphatic Carboxylic Acids.

PubMed

Kautzky, Jacob A; Wang, Tao; Evans, Ryan W; MacMillan, David W C

2018-05-14

Herein we disclose an efficient method for the conversion of carboxylic acids to trifluoromethyl groups via the combination of photoredox and copper catalysis. This transformation tolerates a wide range of functionality including heterocycles, olefins, alcohols, and strained ring systems. To demonstrate the broad potential of this new methodology for late-stage functionalization, we successfully converted a diverse array of carboxylic acid-bearing natural products and medicinal agents to the corresponding trifluoromethyl analogues.

Construction of a recombinant strain of Pseudomonas fluorescens producing both phenazine-1-carboxylic acid and cyclic lipopeptide for the biocontrol of take-all disease of wheat.

USDA-ARS?s Scientific Manuscript database

The primary mechanism of biocontrol by Pseudomonas fluorescens strains HC1-07 and HC9-07 is production of a cyclic lipopeptide (CLP) and phenazine-1-carboxylic acid, respectively. We introduced the seven-gene operon for the synthesis of phenazine-1-carboxylic acid (PCA) from P. synxantha 2-79 into P...

Synthesis of aminocarbonyl N-acylhydrazones by a three-component reaction of isocyanides, hydrazonoyl chlorides, and carboxylic acids.

PubMed

Giustiniano, Mariateresa; Meneghetti, Fiorella; Mercalli, Valentina; Varese, Monica; Giustiniano, Francesco; Novellino, Ettore; Tron, Gian Cesare

2014-10-17

A novel one-pot multicomponent synthesis of α-aminocarbonyl N-acylhydrazones starting from readily available hydrazonoyl chlorides, isocyanides, and carboxylic acids is reported. The strategy exploits the ability of the carboxylic acid as a third component to suppress all competing reactions between nitrile imines and isocyanides, channeling the course of the reaction toward the formation of this novel class of compounds.

Human Lamin B Contains a Farnesylated Cysteine Residue*

PubMed Central

Farnsworth, Christopher C.; Wolda, Sharon L.; Gelb, Michael H.; Glomset, John A.

2012-01-01

We recently showed that HeLa cell lamin B is modified by a mevalonic acid derivative. Here we identified the modified amino acid, determined its mode of link-age to the mevalonic acid derivative, and established the derivative’s structure. A cysteine residue is modified because experiments with lamin B that had been biosynthetically labeled with [3H] mevalonic acid or [35S] cysteine and then extensively digested with proteases yielded 3H- or 35S-labeled products that co-chromatographed in five successive systems. A thioether linkage rather than a thioester linkage is involved because the mevalonic acid derivative could be released from the 3H-labeled products in a pentane-extractable form by treatment with Raney nickel but not with methanolic KOH. The derivative is a farnesyl moiety because the Raney nickel-released material was identified as 2,6,10-trimethyl-2,6,10-dodecatriene by a combination of gas chromatography and mass spectrometry. The thioether-modified cysteine residue appears to be located near the carboxyl end of lamin B because treatment of 3H-labeled lamin B with cyanogen bromide yielded a single labeled polypeptide that mapped toward this end of the cDNA-inferred sequence of human lamin B. PMID:2684976

Determination of Double Bond Positions in Polyunsaturated Fatty Acids Using the Photochemical Paternò-Büchi Reaction with Acetone and Tandem Mass Spectrometry.

PubMed

Murphy, Robert C; Okuno, Toshiaki; Johnson, Christopher A; Barkley, Robert M

2017-08-15

The positions of double bonds along the carbon chain of methylene interrupted polyunsaturated fatty acids are unique identifiers of specific fatty acids derived from biochemical reactions that occur in cells. It is possible to obtain direct structural information as to these double bond positions using tandem mass spectrometry after collisional activation of the carboxylate anions of an acetone adduct at each of the double bond positions formed by the photochemical Paternò-Büchi reaction with acetone. This reaction can be carried out by exposing a small portion of an inline fused silica capillary to UV photons from a mercury vapor lamp as the sample is infused into the electrospray ion source of a mass spectrometer. Collisional activation of [M - H] - yields a series of reverse Paternò-Büchi reaction product ions that essentially are derived from cleavage of the original carbon-carbon double bonds that yield an isopropenyl carboxylate anion corresponding to each double bond location. Aldehydic reverse Paternò-Büchi product ions are much less abundant as the carbon chain length and number of double bonds increase. The use of a mixture of D 0 /D 6 -acetone facilitates identification of these double bonds indicating product ions as shown for arachidonic acid. If oxygen is present in the solvent stream undergoing UV photoactivation, ozone cleavage ions are also observed without prior collisional activation. This reaction was used to determine the double bond positions in a 20:3 fatty acid that accumulated in phospholipids of RAW 264.7 cells cultured for 3 days.

Ion-exclusion chromatography with conductimetric detection of aliphatic carboxylic acids on a weakly acidic cation-exchange resin by elution with benzoic acid-beta-cyclodextrin.

PubMed

Tanaka, Kazuhiko; Mori, Masanobu; Xu, Qun; Helaleh, Murad I H; Ikedo, Mikaru; Taoda, Hiroshi; Hu, Wenzhi; Hasebe, Kiyoshi; Fritz, James S; Haddad, Paul R

2003-05-16

In this study, an aqueous solution consisting of benzoic acid with low background conductivity and beta-cyclodextrin (beta-CD) of hydrophilic nature and the inclusion effect to benzoic acid were used as eluent for the ion-exclusion chromatographic separation of aliphatic carboxylic acids with different pKa values and hydrophobicity on a polymethacrylate-based weakly acidic cation-exchange resin in the H+ form. With increasing concentration of beta-cyclodextrin in the eluent, the retention times of the carboxylic acids decreased due to the increased hydrophilicity of the polymethacrylate-based cation-exchange resin surface from the adsorption of OH groups of beta-cyclodextrin. Moreover, the eluent background conductivity decreased with increasing concentration of beta-cyclodextrin in 1 mM benzoic acid, which could result in higher sensitivity for conductimetric detection. The ion-exclusion chromatographic separation of carboxylic acids with high resolution and sensitivity was accomplished successfully by elution with a 1 mM benzoic acid-10 mM cyclodextrin solution without chemical suppression.

Carboxylator: incorporating solvent-accessible surface area for identifying protein carboxylation sites

NASA Astrophysics Data System (ADS)

Lu, Cheng-Tsung; Chen, Shu-An; Bretaña, Neil Arvin; Cheng, Tzu-Hsiu; Lee, Tzong-Yi

2011-10-01

In proteins, glutamate (Glu) residues are transformed into γ-carboxyglutamate (Gla) residues in a process called carboxylation. The process of protein carboxylation catalyzed by γ-glutamyl carboxylase is deemed to be important due to its involvement in biological processes such as blood clotting cascade and bone growth. There is an increasing interest within the scientific community to identify protein carboxylation sites. However, experimental identification of carboxylation sites via mass spectrometry-based methods is observed to be expensive, time-consuming, and labor-intensive. Thus, we were motivated to design a computational method for identifying protein carboxylation sites. This work aims to investigate the protein carboxylation by considering the composition of amino acids that surround modification sites. With the implication of a modified residue prefers to be accessible on the surface of a protein, the solvent-accessible surface area (ASA) around carboxylation sites is also investigated. Radial basis function network is then employed to build a predictive model using various features for identifying carboxylation sites. Based on a five-fold cross-validation evaluation, a predictive model trained using the combined features of amino acid sequence (AA20D), amino acid composition, and ASA, yields the highest accuracy at 0.874. Furthermore, an independent test done involving data not included in the cross-validation process indicates that in silico identification is a feasible means of preliminary analysis. Additionally, the predictive method presented in this work is implemented as Carboxylator (http://csb.cse.yzu.edu.tw/Carboxylator/), a web-based tool for identifying carboxylated proteins with modification sites in order to help users in investigating γ-glutamyl carboxylation.

6-Substituted 3,4-dihydro-naphthalene-2-carboxylic acids: synthesis and structure-activity studies in a novel class of human 5alpha reductase inhibitors.

PubMed

Baston, Eckhard; Salem, Ola I A; Hartmann, Rolf W

2002-10-01

Novel 3,4-dihydro-naphthalene-2-carboxylic acids were synthesized and evaluated for 5alpha reductase inhibitory activity. This enzyme exists in two isoforms and is a pharmacological target for the treatment of benign prostatic hyperplasia, male pattern baldness and acne. In the present study non-steroidal compounds capable of mimicking the transition state of the steroidal substrates were prepared. The synthetic strategy for the preparation of compounds 1-6 consisted of triflation followed by subsequent Heck-type carboxylation or methoxy carbonylation for 6-phenyl-3,4-dihydronaphthalen-2(1H)-one 1c. A Negishi-type coupling reaction between 6-(trifluoro-methanesulfonyloxy)-3,4-dihydro-naphthalene-2-carboxylic acid methyl ester 7b and various aryl bromides led, after further transformations, to 6-substituted 3,4-dihydro-naphthalene-2-carboxylic acids 7-15. In a similar way the corresponding naphthalene-2-carboxylic acids 16 and 17 were obtained. The DU 145 cell line and prostate homogenates served as enzyme sources for the human type 1 and type 2 isozymes, whereas ventral prostate was employed to evaluate rat isozyme inhibitory potency. The most active inhibitors identified in this study were 6-[4-(N,N-dicyclohexylaminocarbonyl)phenyl]-3,4-dihydro-naphthalene-2-carboxylic acid (3) (IC50 = 0.09 microM, rat type 1), 6-[3-(N,N-dicyclohexylaminocarbonyl)phenyl]-3,4-dihydro-naphthalene-2-carboxylic acid (13) (IC50 = 0.75 microM, human type 2; IC50 = 0.81 microM, human type 1) and 6-[4-(N,N-diisopropylamino-carbonyl)phenyl]naphthalene-2-carboxylic acid (16) (IC50 = 0.2 microM, human type 2). The latter compound was shown to deactivate the enzyme in an uncompetitive manner (Ki = 90 nM; Km, Testosterone = 0.8-1.0 microM) similar to the steroidal inhibitor Epristeride. Select inhibitors (13 and 16) were tested in vivo using testosterone propionate-treated, juvenile, orchiectomized SD-rats. None of the compounds was active at a dose of 25 mg/kg. This result might in part be ascribed to the relatively poor in vitro rat isozyme inhibitory potency.

Analogues of desferrioxamine B designed to attenuate iron-mediated neurodegeneration: synthesis, characterisation and activity in the MPTP-mouse model of Parkinson's disease.

PubMed

Gotsbacher, Michael P; Telfer, Thomas J; Witting, Paul K; Double, Kay L; Finkelstein, David I; Codd, Rachel

2017-07-19

Parkinson's disease (PD) is a neurodegenerative disorder characterised by the death of dopaminergic neurons in the substantia nigra pars compacta (SNpc) region of the brain and formation of α-synuclein-containing intracellular inclusions. Excess intraneuronal iron in the SNpc increases reactive oxygen species (ROS), which identifies removing iron as a possible therapeutic strategy. Desferrioxamine B (DFOB, 1) is an iron chelator produced by bacteria. Its high Fe(iii) affinity, water solubility and low chronic toxicity is useful in removing iron accumulated in plasma from patients with transfusion-dependent blood disorders. Here, lipophilic analogues of DFOB with increased potential to cross the blood-brain barrier (BBB) have been prepared by conjugating ancillary compounds onto the amine terminus. The ancillary compounds included the antioxidants rac-6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid (rac-trolox, rac-TLX (a truncated vitamin E variant)), R-TLX, S-TLX, methylated derivatives of 3-(6-hydroxy-2-methylchroman-2-yl)propionic acid (α-CEHC, γ-CEHC, δ-CEHC), or 4-(5-hydroxy-3-methyl-1H-pyrazol-1-yl)benzoic acid (carboxylic acid derivative of edaravone, EDA). Compounds 2-8 could have dual function in attenuating ROS by chelating Fe(iii) and via the antioxidant ancillary group. A conjugate between DFOB and an ancillary unit without antioxidant properties (3,5-dimethyladamantane-1-carboxylic acid (AdA dMe )) was included (9). Compounds 2-9 were more lipophilic (log P -0.05 to 3.39) than DFOB (log P -2.62) and showed an average plasma protein binding 6 times greater than DFOB. The ABTS˙ + radical assay indicated 2-8 had antioxidant activity ascribable to the ancillary fragment. Administration of 2 and 9 in the mouse model of PD using the neurotoxin prodrug 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), which recapitulates elevated iron of human PD, resulted in significant neuronal protection (p < 0.05; up to 89% of that in non-lesioned control animals), demonstrating the neuroprotective potential of these compounds for PD.

A copper(II) paddle-wheel structure of tranexamic acid: di-chloro-tetra-kis-[μ-4-(ammonio-meth-yl)cyclo-hexane-1-carboxyl-ato-O,O']dicopper(II) dichloride hexa-hydrate.

PubMed

Altaf, Muhammad; Stoeckli-Evans, Helen

2017-10-01

Tranexamic acid [systematic name: trans -4-(amino-meth-yl)cyclo-hexane-1-carb-oxy-lic acid], is an anti-fibrinolytic amino acid that exists as a zwitterion [ trans -4-(ammonio-meth-yl)cyclo-hexane-1-carboxyl-ate] in the solid state. Its reaction with copper chloride leads to the formation of a compound with a copper(II) paddle-wheel structure that crystallizes as a hexa-hydrate, [Cu 2 Cl 2 (C 8 H 15 NO 2 ) 4 ] 2+ ·2Cl - ·6H 2 O. The asymmetric unit is composed of a copper(II) cation, two zwitterionic tranexamic acid units, a coordinating Cl - anion and a free Cl - anion, together with three water mol-ecules of crystallization. The whole structure is generated by inversion symmetry, with the Cu⋯Cu axle of the paddle-wheel dication being located about a center of symmetry. The cyclo-hexane rings of the zwitterionic tranexamic acid units have chair conformations. The carboxyl-ate groups that bridge the two copper(II) cations are inclined to one another by 88.4 (8)°. The copper(II) cation is ligated by four carboxyl-ate O atoms in the equatorial plane and by a Cl - ion in the axial position. Hence, it has a fivefold O 4 Cl coordination sphere with a perfect square-pyramidal geometry and a τ 5 index of zero. In the crystal, the paddle-wheel dications are linked by a series of N-H⋯Cl hydrogen bonds, involving the coordinating and free Cl - ions, forming a three-dimensional network. This network is strengthened by a series of N-H⋯O water , O water -H⋯Cl and O water -H⋯O hydrogen bonds.

Organic acids in naturally colored surface waters

USGS Publications Warehouse

Lamar, William L.; Goerlitz, D.F.

1966-01-01

Most of the organic matter in naturally colored surface waters consists of a mixture of carboxylic acids or salts of these acids. Many of the acids color the water yellow to brown; however, not all of the acids are colored. These acids range from simple to complex, but predominantly they are nonvolatile polymeric carboxylic acids. The organic acids were recovered from the water by two techniques: continuous liquid-liquid extraction with n-butanol and vacuum evaporation at 50?C (centigrade). The isolated acids were studied by techniques of gas, paper, and column chromatography and infrared spectroscopy. About 10 percent of the acids recovered were volatile or could be made volatile for gas chromatographic analysis. Approximately 30 of these carboxylic acids were isolated, and 13 of them were individually identified. The predominant part of the total acids could not be made volatile for gas chromatographic analysis. Infrared examination of many column chromatographic fractions indicated that these nonvolatile substances are primarily polymeric hydroxy carboxylic acids having aromatic and olefinic unsaturation. The evidence suggests that some of these acids result from polymerization in aqueous solution. Elemental analysis of the sodium fusion products disclosed the absence of nitrogen, sulfur, and halogens.

Selective reduction of carboxylic acids to aldehydes with hydrosilane via photoredox catalysis.

PubMed

Zhang, Muliang; Li, Nan; Tao, Xingyu; Ruzi, Rehanguli; Yu, Shouyun; Zhu, Chengjian

2017-09-12

The direct reduction of carboxylic acids to aldehydes with hydrosilane was achieved through visible light photoredox catalysis. The combination of both single electron transfer and hydrogen atom transfer steps offers a novel and convenient approach to selective reduction of carboxylic acids to aldehydes. The method also features mild conditions, high yields, broad substrate scope, and good functional group tolerance, such as alkyne, ester, ketone, amide and amine groups.

Highly Selective Deoxydehydration of Tartaric Acid over Supported and Unsupported Rhenium Catalysts with Modified Acidities.

PubMed

Li, Xiukai; Zhang, Yugen

2016-10-06

The deoxydehydration (DODH) of sugar acids to industrially important carboxylic acids is a very attractive topic. Oxorhenium complexes are the most-often employed DODH catalysts. Because of the acidity of the rhenium catalysts, the DODH products of sugar acids were usually in the form of mixture of free carboxylic acids and esters. Herein, we demonstrate strategies for the selective DODH of sugar acids to free carboxylic acids by tuning the Lewis acidity or the Brønsted acidity of the rhenium-based catalysts. Starting from tartaric acid, up to 97 % yield of free maleic acid was achieved. Based on our strategies, functional polymer immobilized heterogeneous rhenium catalysts were also developed for the selective DODH conversion of sugar acids. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation of .alpha., .beta.-unsaturated carboxylic acids and anhydrides

DOEpatents

Spivey, James Jerry; Gogate, Makarand Ratnakav; Zoeller, Joseph Robert; Tustin, Gerald Charles

1998-01-01

Disclosed is a process for the preparation of .alpha.,.beta.-unsaturated carboxylic acids and anhydrides thereof which comprises contacting formaldehyde or a source of formaldehyde with a carboxylic anhydride in the presence of a catalyst comprising mixed oxides of vanadium, phosphorus and, optionally, a third component selected from titanium, aluminum or, preferably silicon.

Preparation of {alpha}, {beta}-unsaturated carboxylic acids and anhydrides

DOEpatents

Spivey, J.J.; Gogate, M.R.; Zoeller, J.R.; Tustin, G.C.

1998-01-20

Disclosed is a process for the preparation of {alpha},{beta}-unsaturated carboxylic acids and anhydrides thereof which comprises contacting formaldehyde or a source of formaldehyde with a carboxylic anhydride in the presence of a catalyst comprising mixed oxides of vanadium, phosphorus and, optionally, a third component selected from titanium, aluminum or, preferably silicon.

Determination of Perfluorocarboxylic Acids in Sludge

EPA Science Inventory

Methods were developed for the extraction from wastewater-treatment sludge and quantitation by LC/MS/MS of perfluorocarboxylic acids (PFCAs, C6 to C12), 7-3 fluorotelomer carboxylic acid (7-3 FTCA) and 8-2 fluorotelomer 2-unsaturated carboxylic acid (8-2 FTUCA) using LC/MS/MS.

Chitosan impregnation with biologically active tryaryl imidazoles in supercritical carbon dioxide.

PubMed

Cherkasova, Anastasia V; Glagolev, Nikolay N; Shienok, Andrey I; Demina, Tatiana S; Kotova, Svetlana L; Zaichenko, Natalia L; Akopova, Tatiana A; Timashev, Peter S; Bagratashvili, Victor N; Solovieva, Anna B

2016-09-01

The presented paper is focused on impregnation of chitosan and its derivatives with a biologically active triaryl imidazole model compound ((2-2-hydroxyphenyl)-4.5-diphenyl-1H-imidazole) in the supercritical carbon dioxide medium. Since initial chitosan represents a polycation-exchange resin and does not swell in supercritical carbon dioxide, the impregnation was carried out in the presence of water (0.15-3.0 vol%). The maximum 2-2-hydroxyphenyl)-4.5-diphenyl-1H-imidazole concentration in a chitosan film was achieved at the ~5 × 10(-3) g/cm(3) water content in the reactor. We also used hydroxy carboxylic acid derivatives of chitosan and its copolymer with polylactide as matrices for introduction of hydrophobic 2-2-hydroxyphenyl)-4.5-diphenyl-1H-imidazole. We have shown that unmodified chitosan contains the greatest amount of 2-2-hydroxyphenyl)-4.5-diphenyl-1H-imidazole, as compared with its hydrophobic derivatives. The kinetics of 2-2-hydroxyphenyl)-4.5-diphenyl-1H-imidazole diffusion from a chitosan matrix was studied in acidified water with pH 1.6. We found that the complete release of 2-2-hydroxyphenyl)-4.5-diphenyl-1H-imidazole into the aqueous phase from unmodified chitosan films occurred in 48 h, while its complete release from chitosan modified with hydroxy carboxylic acids occurred in 5 min or less.

From ether to acid: A plausible degradation pathway of glycerol dialkyl glycerol tetraethers

NASA Astrophysics Data System (ADS)

Liu, Xiao-Lei; Birgel, Daniel; Elling, Felix J.; Sutton, Paul A.; Lipp, Julius S.; Zhu, Rong; Zhang, Chuanlun; Könneke, Martin; Peckmann, Jörn; Rowland, Steven J.; Summons, Roger E.; Hinrichs, Kai-Uwe

2016-06-01

Glycerol dialkyl glycerol tetraethers (GDGTs) are ubiquitous microbial lipids with extensive demonstrated and potential roles as paleoenvironmental proxies. Despite the great attention they receive, comparatively little is known regarding their diagenetic fate. Putative degradation products of GDGTs, identified as hydroxyl and carboxyl derivatives, were detected in lipid extracts of marine sediment, seep carbonate, hot spring sediment and cells of the marine thaumarchaeon Nitrosopumilus maritimus. The distribution of GDGT degradation products in environmental samples suggests that both biotic and abiotic processes act as sinks for GDGTs. More than a hundred newly recognized degradation products afford a view of the stepwise degradation of GDGT via (1) ether bond hydrolysis yielding hydroxyl isoprenoids, namely, GDGTol (glycerol dialkyl glycerol triether alcohol), GMGD (glycerol monobiphytanyl glycerol diether), GDD (glycerol dibiphytanol diether), GMM (glycerol monobiphytanol monoether) and bpdiol (biphytanic diol); (2) oxidation of isoprenoidal alcohols into corresponding carboxyl derivatives and (3) chain shortening to yield C39 and smaller isoprenoids. This plausible GDGT degradation pathway from glycerol ethers to isoprenoidal fatty acids provides the link to commonly detected head-to-head linked long chain isoprenoidal hydrocarbons in petroleum and sediment samples. The problematic C80 to C82 tetraacids that cause naphthenate deposits in some oil production facilities can be generated from H-shaped glycerol monoalkyl glycerol tetraethers (GMGTs) following the same process, as indicated by the distribution of related derivatives in hydrothermally influenced sediments.

PCI-GC-MS-MS approach for identification of non-amino organic acid and amino acid profiles.

PubMed

Luan, Hemi; Yang, Lin; Ji, Fenfen; Cai, Zongwei

2017-03-15

Alkyl chloroformate have been wildly used for the fast derivatization of metabolites with amino and/or carboxyl groups, coupling of powerful separation and detection systems, such as GC-MS, which allows the comprehensive analysis of non-amino organic acids and amino acids. The reagents involving n-alkyl chloroformate and n-alcohol are generally employed for providing symmetric labeling terminal alkyl chain with the same length. Here, we developed an asymmetric labeling strategy and positive chemical ionization gas chromatography-tandem mass spectrometry (PCI-GC-MS-MS) approach for determination of non-amino organic acids and amino acids, as well as the short chain fatty acids. Carboxylic and amino groups could be selectively labelled by propyl and ethyl groups, respectively. The specific neutral loss of C 3 H 8 O (60Da), C 3 H 5 O 2 (74Da) and C 4 H 8 O 2 (88Da) were useful in the selective identification for qualitative analysis of organic acids and amino acid derivatives. PCI-GC-MS-MS using multiple reaction monitoring (MRM) was applied for semi-quantification of typical non-amino organic acids and amino acids. This method exhibited a wide range of linear range, good regression coefficient (R 2 ) and repeatability. The relative standard deviation (RSD) of targeted metabolites showed excellent intra- and inter-day precision (<5%). Our method provided a qualitative and semi-quantitative PCI-GC-MS-MS, coupled with alkyl chloroformate derivatization. Copyright © 2016 Elsevier B.V. All rights reserved.

Analysis of Organic Acids.

ERIC Educational Resources Information Center

Griswold, John R.; Rauner, Richard A.

1990-01-01

Presented are the procedures and a discussion of the results for an experiment in which students select unknown carboxylic acids, determine their melting points, and investigate their solubility behavior in water and ethanol. A table of selected carboxylic acids is included. (CW)

Probes of the catalytic site of cysteine dioxygenase.

PubMed

Chai, Sergio C; Bruyere, John R; Maroney, Michael J

2006-06-09

The first major step of cysteine catabolism, the oxidation of cysteine to cysteine sulfinic acid, is catalyzed by cysteine dioxygenase (CDO). In the present work, we utilize recombinant rat liver CDO and cysteine derivatives to elucidate structural parameters involved in substrate recognition and x-ray absorption spectroscopy to probe the interaction of the active site iron center with cysteine. Kinetic studies using cysteine structural analogs show that most are inhibitors and that a terminal functional group bearing a negative charge (e.g. a carboxylate) is required for binding. The substrate-binding site has no stringent restrictions with respect to the size of the amino acid. Lack of the amino or carboxyl groups at the alpha-carbon does not prevent the molecules from interacting with the active site. In fact, cysteamine is shown to be a potent activator of the enzyme without being a substrate. CDO was also rendered inactive upon complexation with the metal-binding inhibitors azide and cyanide. Unlike many non-heme iron dioxygenases that employ alpha-keto acids as cofactors, CDO was shown to be the only dioxygenase known to be inhibited by alpha-ketoglutarate.

Effect of Amine Modification on the Properties of Zirconium-Carboxylic Acid Based Materials and Their Applications as NO2 Adsorbents at Ambient Conditions

DTIC Science & Technology

2014-01-06

as a source of –SH [23]. Nitrogen dioxide (NO2) is an acidic , corrosive , and toxic gas present in the atmosphere. The main sources of NO2 pollution is...occurring are the Lewis acid –base reactions. These reactions are facilitated by the formation of nitric Schematic reaction between the urea incorporated in...of zirconium– carboxylic acid based materials and their applications as NO2 adsorbents at ambient conditions Zirconium–carboxylic ligand-based porous

Production of alpha-hydroxy carboxylic acids and esters from higher sugars using tandem catalyst systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Orazov, Marat; Davis, Mark E.

The present disclosure is directed to methods and composition used in the preparation of alpha-hydroxy carboxylic acids and esters from higher sugars using a tandem catalyst system comprising retro-aldol catalysts and Lewis acid catalysts. In some embodiments, these alpha-hydroxy carboxylic acids may be prepared from pentoses and hexoses. The retro-aldol and Lewis catalysts may be characterized by their respective ability to catalyze a 1,2-carbon shift reaction and a 1,2-hydride shift reaction on an aldose or ketose substrate.

Structural basis for 18-β-glycyrrhetinic acid as a novel non-GSH analog glyoxalase I inhibitor.

PubMed

Zhang, Hong; Huang, Qiang; Zhai, Jing; Zhao, Yi-ning; Zhang, Li-ping; Chen, Yun-yun; Zhang, Ren-wei; Li, Qing; Hu, Xiao-peng

2015-09-01

Glyoxalase I (GLOI), a glutathione (GSH)-dependent enzyme, is overexpressed in tumor cells and related to multi-drug resistance in chemotherapy, making GLOI inhibitors as potential anti-tumor agents. But the most studied GSH analogs exhibit poor pharmacokinetic properties. The aim of this study was to discover novel non-GSH analog GLOI inhibitors and analyze their binding mechanisms. Mouse GLOI (mGLOI) was expressed in BL21 (DE3) pLysS after induction with isopropyl-β-D-1-thiogalactopyranoside and purified using AKTA FPLC system. An in vitro mGLOI enzyme assay was used to screen a small pool of compounds containing carboxyl groups. Crystal structure of the mGLOI-inhibitor complex was determined at 2.3 Å resolution. Molecular docking study was performed using Discovery Studio 2.5 software package. A natural compound 18-β-glycyrrhetinic acid (GA) and its derivative carbenoxolone were identified as potent competitive non-GSH analog mGLOI inhibitors with Ki values of 0.29 μmol/L and 0.93 μmol/L, respectively. Four pentacyclic triterpenes (ursolic acid, oleanolic acid, betulic acid and tripterine) showed weak activities (mGLOI inhibition ratio <25% at 10 μmol/L) and other three (maslinic acid, corosolic acid and madecassic acid) were inactive. The crystal structure of the mGLOI-GA complex showed that the carboxyl group of GA mimicked the γ-glutamyl residue of GSH by hydrogen bonding to the glutamyl sites (residues Arg38B, Asn104B and Arg123A) in the GSH binding site of mGLOI. The extensive van der Waals interactions between GA and the surrounding residues also contributed greatly to the binding of GA and mGLOI. This work demonstrates a carboxyl group to be an important functional feature of non-GSH analog GLOI inhibitors.

Polyhydroxyalkanoate-based 3-hydroxyoctanoic acid and its derivatives as a platform of bioactive compounds.

PubMed

Radivojevic, Jelena; Skaro, Sanja; Senerovic, Lidija; Vasiljevic, Branka; Guzik, Maciej; Kenny, Shane T; Maslak, Veselin; Nikodinovic-Runic, Jasmina; O'Connor, Kevin E

2016-01-01

A library of 18 different compounds was synthesized starting from (R)-3-hydroxyoctanoic acid which is derived from the bacterial polymer polyhydroxyalkanoate (PHA). Ten derivatives, including halo and unsaturated methyl and benzyl esters, were synthesized and characterized for the first time. Given that (R)-3-hydroxyalkanoic acids are known to have biological activity, the new compounds were evaluated for antimicrobial activity and in vitro antiproliferative effect with mammalian cell lines. The presence of the carboxylic group was essential for the antimicrobial activity, with minimal inhibitory concentrations against a panel of bacteria (Gram-positive and Gram-negative) and fungi (Candida albicans and Microsporum gypseum) in the range 2.8-7.0 mM and 0.1-6.3 mM, respectively. 3-Halogenated octanoic acids exhibited the ability to inhibit C. albicans hyphae formation. In addition, (R)-3-hydroxyoctanoic and (E)-oct-2-enoic acids inhibited quorum sensing-regulated pyocyanin production in the opportunistic pathogen Pseudomonas aeruginosa PAO1. Generally, derivatives did not inhibit mammalian cell proliferation even at 3-mM concentrations, while only (E)-oct-2-enoic and 3-oxooctanoic acid had IC50 values of 1.7 and 1.6 mM with the human lung fibroblast cell line.

ANALYSIS OF PERFLUORINATED CARBOXYLIC ACIDS IN SOILS II: OPTIMIZATION OF CHROMATOGRAPHY AND EXTRACTION

EPA Science Inventory

With the objective of detecting and quantitating low concentrations of perfluorinated carboxylic acids (PFCAs), including perfluorinated octanoic acid (PFOA), in soils, we compared the analytical suitability of liquid chromatography columns containing three different stationary p...

Metal-free one-pot oxidative amination of aldehydes to amides.

PubMed

Ekoue-Kovi, Kekeli; Wolf, Christian

2007-08-16

Metal-free oxidative amination of aromatic aldehydes in the presence of TBHP provides convenient access to amides in 85-99% under mild reaction conditions within 5 h. This method avoids free carboxylic acid intermediates and integrates aldehyde oxidation and amide bond formation, which are usually accomplished separately, into a single operation. Proline-derived amides can be prepared in excellent yields without noticeable racemization.

The Hypothesis that the Genetic Code Originated in Coupled Synthesis of Proteins and the Evolutionary Predecessors of Nucleic Acids in Primitive Cells

PubMed Central

Francis, Brian R.

2015-01-01

Although analysis of the genetic code has allowed explanations for its evolution to be proposed, little evidence exists in biochemistry and molecular biology to offer an explanation for the origin of the genetic code. In particular, two features of biology make the origin of the genetic code difficult to understand. First, nucleic acids are highly complicated polymers requiring numerous enzymes for biosynthesis. Secondly, proteins have a simple backbone with a set of 20 different amino acid side chains synthesized by a highly complicated ribosomal process in which mRNA sequences are read in triplets. Apparently, both nucleic acid and protein syntheses have extensive evolutionary histories. Supporting these processes is a complex metabolism and at the hub of metabolism are the carboxylic acid cycles. This paper advances the hypothesis that the earliest predecessor of the nucleic acids was a β-linked polyester made from malic acid, a highly conserved metabolite in the carboxylic acid cycles. In the β-linked polyester, the side chains are carboxylic acid groups capable of forming interstrand double hydrogen bonds. Evolution of the nucleic acids involved changes to the backbone and side chain of poly(β-d-malic acid). Conversion of the side chain carboxylic acid into a carboxamide or a longer side chain bearing a carboxamide group, allowed information polymers to form amide pairs between polyester chains. Aminoacylation of the hydroxyl groups of malic acid and its derivatives with simple amino acids such as glycine and alanine allowed coupling of polyester synthesis and protein synthesis. Use of polypeptides containing glycine and l-alanine for activation of two different monomers with either glycine or l-alanine allowed simple coded autocatalytic synthesis of polyesters and polypeptides and established the first genetic code. A primitive cell capable of supporting electron transport, thioester synthesis, reduction reactions, and synthesis of polyesters and polypeptides is proposed. The cell consists of an iron-sulfide particle enclosed by tholin, a heterogeneous organic material that is produced by Miller-Urey type experiments that simulate conditions on the early Earth. As the synthesis of nucleic acids evolved from β-linked polyesters, the singlet coding system for replication evolved into a four nucleotide/four amino acid process (AMP = aspartic acid, GMP = glycine, UMP = valine, CMP = alanine) and then into the triplet ribosomal process that permitted multiple copies of protein to be synthesized independent of replication. This hypothesis reconciles the “genetics first” and “metabolism first” approaches to the origin of life and explains why there are four bases in the genetic alphabet. PMID:25679748

Rapid Screening of Carboxylic Acids from Waste and Surface Waters by ESI-MS/MS Using Barium Ion Chemistry and On-Line Membrane Sampling.

PubMed

Duncan, Kyle D; Volmer, Dietrich A; Gill, Chris G; Krogh, Erik T

2016-03-01

Negative ion tandem mass spectrometric analysis of aliphatic carboxylic acids often yields only non-diagnostic ([M - H](-)) ions with limited selective fragmentation. However, carboxylates cationized with Ba(2+) have demonstrated efficient dissociation in positive ion mode, providing structurally diagnostic product ions. We report the application of barium adducts followed by collision induced dissociation (CID), to improve selectivity for rapid screening of carboxylic acids in complex aqueous samples. The quantitative MS/MS method presented utilizes common product ions of [M - H + Ba](+) precursor ions. The mechanism of product ion formation is investigated using isotopically labeled standards and a series of structurally related carboxylic acids. The results suggest that hydrogen atoms in the β and γ positions yield common product ions ([BaH](+) and [BaOH](+)). Furthermore, the diagnostic product ion at m/z 196 serves as a qualifying ion for carboxylate species. This methodology has been successfully used in conjunction with condensed phase membrane introduction mass spectrometry (CP-MIMS), with barium acetate added directly to the methanol acceptor phase. The combination enables rapid screening of carboxylic acids directly from acidified water samples (wastewater effluent, spiked natural waters) using a capillary hollow fiber PDMS membrane immersion probe. We have applied this technique for the direct analysis of complex naphthenic acid mixtures spiked into natural surface waters using CP-MIMS. Selectivity at the ionization and tandem mass spectrometry level eliminate isobaric interferences from hydroxylated species present within the samples, which have been observed in negative electrospray ionization.

Separation of aliphatic carboxylic acids and benzenecarboxylic acids by ion-exclusion chromatography with various cation-exchange resin columns and sulfuric acid as eluent.

PubMed

Ohta, Kazutoku; Ohashi, Masayoshi; Jin, Ji-Ye; Takeuchi, Toyohide; Fujimoto, Chuzo; Choi, Seong-Ho; Ryoo, Jae-Jeong; Lee, Kwang-Pill

2003-05-16

The application of various hydrophilic cation-exchange resins for high-performance liquid chromatography (sulfonated silica gel: TSKgel SP-2SW, carboxylated silica gel: TSKgel CM-2SW, sulfonated polymethacrylate resin: TSKgel SP-5PW, carboxylated polymethacrylate resins: TSKgel CM-5PW and TSKgel OA-Pak A) as stationary phases in ion-exclusion chromatography for C1-C7 aliphatic carboxylic acids (formic, acetic, propionic, butyric, isovaleric, valeric, isocaproic, caproic, 2-methylhexanoic and heptanoic acids) and benzenecarboxylic acids (pyromellitic, trimellitic, hemimellitic, o-phthalic, m-phthalic, p-phthalic, benzoic, salicylic acids and phenol) was carried out using diluted sulfuric acid as the eluent. Silica-based cation-exchange resins (TSKgel SP-2SW and TSKgel CM-2SW) were very suitable for the ion-exclusion chromatographic separation of these benzenecarboxylic acids. Excellent simultaneous separation of these benzenecarboxylic acids was achieved on a TSKgel SP-2SW column (150 x 6 mm I.D.) in 17 min using a 2.5 mM sulfuric acid at pH 2.4 as the eluent. Polymethacrylate-based cation-exchange resins (TSKgel SP-5PW, TSKgel CM-5PW and TSKgel OA-Pak A) acted as advanced stationary phases for the ion-exclusion chromatographic separation of these C1-C7 aliphatic carboxylic acids. Excellent simultaneous separation of these C1-C7 acids was achieved on a TSKgel CM-5PW column (150 x 6 mm I.D.) in 32 min using a 0.05 mM sulfuric acid at pH 4.0 as the eluent.

Microbial Transformation of Esters of Chlorinated Carboxylic Acids

PubMed Central

Paris, D. F.; Wolfe, N. L.; Steen, W. C.

1984-01-01

Two groups of compounds were selected for microbial transformation studies. In the first group were carboxylic acid esters having a fixed aromatic moiety and an increasing length of the alkyl component. Ethyl esters of chlorine-substituted carboxylic acids were in the second group. Microorganisms from environmental waters and a pure culture of Pseudomonas putida U were used. The bacterial populations were monitored by plate counts, and disappearance of the parent compound was followed by gas-liquid chromatography as a function of time. The products of microbial hydrolysis were the respective carboxylic acids. Octanol-water partition coefficients (Kow) for the compounds were measured. These values spanned three orders of magnitude, whereas microbial transformation rate constants (kb) varied only 50-fold. The microbial rate constants of the carboxylic acid esters with a fixed aromatic moiety increased with an increasing length of alkyl substituents. The regression coefficient for the linear relationships between log kb and log Kow was high for group 1 compounds, indicating that these parameters correlated well. The regression coefficient for the linear relationships for group 2 compounds, however, was low, indicating that these parameters correlated poorly. PMID:16346459

Engineering of Saccharomyces cerevisiae for the synthesis of short chain fatty acids.

PubMed

Leber, Christopher; Da Silva, Nancy A

2014-02-01

Carbon feedstocks from fossilized sources are being rapidly depleted due to rising demand for industrial and commercial applications. Many petroleum-derived chemicals can be directly or functionally substituted with chemicals derived from renewable feedstocks. Several short chain organic acids may fulfill this role using their functional groups as a target for chemical catalysis. Saccharomyces cerevisiae was engineered to produce short chain carboxylic acids (C6 to C10 ) from glucose using the heterologous Homo sapiens type I fatty acid synthase (hFAS). This synthase was activated by phosphopantetheine transfereases AcpS and Sfp from Escherichia coli and Bacillus subtilis, respectively, both in vitro and in vivo. hFAS was produced in the holo-form and produced carboxylic acids in vitro, confirmed by NADPH and ADIFAB assays. Overexpression of hFAS in a yeast FAS2 knockout strain, deficient in de novo fatty acid synthesis, demonstrated the full functional replacement of the native fungal FAS by hFAS. Two active heterologous short chain thioesterases (TEs) from Cuphea palustris (CpFatB1) and Rattus norvegicus (TEII) were evaluated for short chain fatty acid (SCFA) synthesis in vitro and in vivo. Three hFAS mutants were constructed: a mutant deficient in the native TE domain, a mutant with a linked CpFatB1 TE and a mutant with a linked TEII TE. Using the native yeast fatty acid synthase for growth, the overexpression of the hFAS mutants and the short-chain TEs (linked or plasmid-based) increased in vivo caprylic acid and total SCFA production up to 64-fold (63 mg/L) and 52-fold (68 mg/L), respectively, over the native yeast levels. Combined over-expression of the phosphopantetheine transferase with the hFAS mutant resulted in C8 titers of up to 82 mg/L and total SCFA titers of up to 111 mg/L. © 2013 Wiley Periodicals, Inc.

Prediction of Protein Modification Sites of Pyrrolidone Carboxylic Acid Using mRMR Feature Selection and Analysis

PubMed Central

Zheng, Lu-Lu; Niu, Shen; Hao, Pei; Feng, KaiYan; Cai, Yu-Dong; Li, Yixue

2011-01-01

Pyrrolidone carboxylic acid (PCA) is formed during a common post-translational modification (PTM) of extracellular and multi-pass membrane proteins. In this study, we developed a new predictor to predict the modification sites of PCA based on maximum relevance minimum redundancy (mRMR) and incremental feature selection (IFS). We incorporated 727 features that belonged to 7 kinds of protein properties to predict the modification sites, including sequence conservation, residual disorder, amino acid factor, secondary structure and solvent accessibility, gain/loss of amino acid during evolution, propensity of amino acid to be conserved at protein-protein interface and protein surface, and deviation of side chain carbon atom number. Among these 727 features, 244 features were selected by mRMR and IFS as the optimized features for the prediction, with which the prediction model achieved a maximum of MCC of 0.7812. Feature analysis showed that all feature types contributed to the modification process. Further site-specific feature analysis showed that the features derived from PCA's surrounding sites contributed more to the determination of PCA sites than other sites. The detailed feature analysis in this paper might provide important clues for understanding the mechanism of the PCA formation and guide relevant experimental validations. PMID:22174779

Biomimetic L-aspartic acid-derived functional poly(ester amide)s for vascular tissue engineering.

PubMed

Knight, Darryl K; Gillies, Elizabeth R; Mequanint, Kibret

2014-08-01

Functionalization of polymeric biomaterials permits the conjugation of cell signaling molecules capable of directing cell function. In this study, l-phenylalanine and l-aspartic acid were used to synthesize poly(ester amide)s (PEAs) with pendant carboxylic acid groups through an interfacial polycondensation approach. Human coronary artery smooth muscle cell (HCASMC) attachment, spreading and proliferation was observed on all PEA films. Vinculin expression at the cell periphery suggested that HCASMCs formed focal adhesions on the functional PEAs, while the absence of smooth muscle α-actin (SMαA) expression implied the cells adopted a proliferative phenotype. The PEAs were also electrospun to yield nanoscale three-dimensional (3-D) scaffolds with average fiber diameters ranging from 130 to 294nm. Immunoblotting studies suggested a potential increase in SMαA and calponin expression from HCASMCs cultured on 3-D fibrous scaffolds when compared to 2-D films. X-ray photoelectron spectroscopy and immunofluorescence demonstrated the conjugation of transforming growth factor-β1 to the surface of the functional PEA through the pendant carboxylic acid groups. Taken together, this study demonstrates that PEAs containing aspartic acid are viable biomaterials for further investigation in vascular tissue engineering. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

An enhanced procedure for measuring organic acids and methyl esters in PM2.5

NASA Astrophysics Data System (ADS)

Liu, F.; Duan, F. K.; He, K. B.; Ma, Y. L.; Rahn, K. A.; Zhang, Q.

2015-11-01

A solid-phase extraction (SPE) pretreatment procedure allowing organic acids to be separated from methyl esters in fine aerosol has been developed. The procedure first separates the organic acids from fatty acid methyl esters (FAMEs) and other nonacid organic compounds by aminopropyl-based SPE cartridge and then quantifies them by gas chromatography/mass spectrometry. The procedure prevents the fatty acids and dimethyl phthalate from being overestimated, and so allows us to accurately quantify the C4-C11 dicarboxylic acids (DCAs) and the C8-C30 monocarboxylic acids (MCAs). Results for the extraction of DCAs, MCAs, and AMAs in eluate and FAMEs in effluate by SAX and NH2 SPE cartridges exhibited that the NH2 SPE cartridge gave higher extraction efficiency than the SAX cartridge. The recoveries of analytes ranged from 67.5 to 111.3 %, and the RSD ranged from 0.7 to 10.9 %. The resulting correlations between the aliphatic acids and FAMEs suggest that the FAMEs had sources similar to those of the carboxylic acids, or were formed by esterifying carboxylic acids, or that aliphatic acids were formed by hydrolyzing FAMEs. Through extraction and cleanup using this procedure, 17 aromatic acids in eluate were identified and quantified by gas chromatography/tandem mass spectrometry, including five polycyclic aromatic hydrocarbon (PAH): acids 2-naphthoic, biphenyl-4-carboxylic, 9-oxo-9H-fluorene-1-carboxylic, biphenyl-4,4´-dicarboxylic, and phenanthrene-1-carboxylic acid, plus 1,8-naphthalic anhydride. Correlations between the PAH acids and the dicarboxylic and aromatic acids suggested that the first three acids and 1,8-naphthalic anhydride were secondary atmospheric photochemistry products and the last two mainly primary.

Functionalised carboxylic acids in atmospheric particles: An annual cycle revealing seasonal trends and possible sources

NASA Astrophysics Data System (ADS)

Teich, Monique; van Pinxteren, Dominik; Herrmann, Hartmut

2013-04-01

Carboxylic acids represent a major fraction of the water soluble organic carbon (WSOC) in atmospheric particles. Among the particle phase carboxylic acids, straight-chain monocarboxylic acids (MCA) and dicarboxylic acids (DCA) with 2-10 carbon atoms have extensively been studied in the past. However, only a few studies exist dealing with functionalised carboxylic acids, i.e. having additional hydroxyl-, oxo- or nitro-groups. Regarding atmospheric chemistry, these functionalised carboxylic acids are of particular interest as they are supposed to be formed during atmospheric oxidation processes, e.g. through radical reactions. Therefore they can provide insights into the tropospheric multiphase chemistry. During this work 28 carboxylic acids (4 functionalised aliphatic MCAs, 5 aromatic MCAs, 3 nitroaromatic MCAs, 6 aliphatic DCAs, 6 functionalised aliphatic DCAs, 4 aromatic DCAs) were quantitatively determined in 256 filter samples taken at the rural research station Melpitz (Saxony, Germany) with a PM10 Digitel DHA-80 filter sampler. All samples were taken in 2010 covering a whole annual cycle. The resulting dataset was examined for a possible seasonal dependency of the acid concentrations. Furthermore the influence of the air mass origin on the acid concentrations was studied based on a simple two-sector classification (western or eastern sector) using a back trajectory analysis. Regarding the annual average, adipic acid was found to be the most abundant compound with a mean concentration of 7.8 ng m-3 followed by 4-oxopimelic acid with 6.1 ng m-3. The sum of all acid concentrations showed two maxima during the seasonal cycle; one in summer and one in winter, whereas the highest overall acid concentrations were found in summer. In general the target acids could be divided into two different groups, where one group has its maximum concentration in summer and the other group during winter. The first group contains all investigated aliphatic mono- and dicarboxylic acids. The high concentrations in summer could lead to the conclusion that these acids are mostly formed during photochemical processes in the atmosphere. However, the concentrations in autumn were often exceeded by the ones in winter. Therefore probably other sources beside photochemical processes have to be considered. The second group consists of aromatic compounds. Because of the high concentrations in winter it can be concluded that photochemical formation plays a minor role and primary emission sources e.g., wood combustion are likely. Further evidence in determining sources of the carboxylic acids could be obtained from the air mass origin. In general, air masses transported from East have a more anthropogenic influence than the air mass inflow from West. For all aromatic carboxylic acids higher concentrations were determined during eastern inflow, indicating anthropogenic sources. This presumption is supported by high correlations with the elemental carbon (EC). Regarding the aliphatic carboxylic there is one group with higher concentrations when the air mass is transported from West and one with higher concentrations when air mass is transported from East. In summary the findings of this study reveal a clear difference in the seasonal trends of the single target acids indicating a variety of different sources.

Strong-acid, carboxyl-group structures in fulvic acid from the Suwannee River, Georgia. 2. Major structures

USGS Publications Warehouse

Leenheer, J.A.; Wershaw, R. L.; Reddy, M.M.

1995-01-01

Polycarboxylic acid structures that account for the strong-acid characteristics (pKa1 near 2.0) were examined for fulvic acid from the Suwannee River. Studies of model compounds demonstrated that pKa values near 2.0 occur only if the ??-ether or ??-ester groups were in cyclic structures with two to three additional electronegative functional groups (carboxyl, ester, ketone, aromatic groups) at adjacent positions on the ring. Ester linkage removal by alkaline hydrolysis and destruction of ether linkages through cleavage and reduction with hydriodic acid confirmed that the strong carboxyl acidity in fulvic acid was associated with polycarboxylic ??-ether and ??-ester structures. Studies of hypothetical structural models of fulvic acid indicated possible relation of these polycarboxylic structures with the amphiphilic and metal-binding properties of fulvic acid.

Direct Enantioselective Conjugate Addition of Carboxylic Acids with Chiral Lithium Amides as Traceless Auxiliaries

PubMed Central

2016-01-01

Michael addition is a premier synthetic method for carbon–carbon and carbon–heteroatom bond formation. Using chiral dilithium amides as traceless auxiliaries, we report the direct enantioselective Michael addition of carboxylic acids. A free carboxyl group in the product provides versatility for further functionalization, and the chiral reagent can be readily recovered by extraction with aqueous acid. The method has been applied in the enantioselective total synthesis of the purported structure of pulveraven B. PMID:25562717

Direct enantioselective conjugate addition of carboxylic acids with chiral lithium amides as traceless auxiliaries.

PubMed

Lu, Ping; Jackson, Jeffrey J; Eickhoff, John A; Zakarian, Armen

2015-01-21

Michael addition is a premier synthetic method for carbon-carbon and carbon-heteroatom bond formation. Using chiral dilithium amides as traceless auxiliaries, we report the direct enantioselective Michael addition of carboxylic acids. A free carboxyl group in the product provides versatility for further functionalization, and the chiral reagent can be readily recovered by extraction with aqueous acid. The method has been applied in the enantioselective total synthesis of the purported structure of pulveraven B.

Profiles of the biosynthesis and metabolism of pyridine nucleotides in potatoes (Solanum tuberosum L.).

PubMed

Katahira, Riko; Ashihara, Hiroshi

2009-12-01

As part of a research program on nucleotide metabolism in potato tubers (Solanum tuberosum L.), profiles of pyridine (nicotinamide) metabolism were examined based on the in situ metabolic fate of radio-labelled precursors and the in vitro activities of enzymes. In potato tubers, [(3)H]quinolinic acid, which is an intermediate of de novo pyridine nucleotide synthesis, and [(14)C]nicotinamide, a catabolite of NAD, were utilised for pyridine nucleotide synthesis. The in situ tracer experiments and in vitro enzyme assays suggest the operation of multiple pyridine nucleotide cycles. In addition to the previously proposed cycle consisting of seven metabolites, we found a new cycle that includes newly discovered nicotinamide riboside deaminase which is also functional in potato tubers. This cycle bypasses nicotinamide and nicotinic acid; it is NAD --> nicotinamide mononucleotide --> nicotinamide riboside --> nicotinic acid riboside --> nicotinic acid mononucleotide --> nicotinic acid adenine dinucleotide --> NAD. Degradation of the pyridine ring was extremely low in potato tubers. Nicotinic acid glucoside is formed from nicotinic acid in potato tubers. Comparative studies of [carboxyl-(14)C]nicotinic acid metabolism indicate that nicotinic acid is converted to nicotinic acid glucoside in all organs of potato plants. Trigonelline synthesis from [carboxyl-(14)C]nicotinic acid was also found. Conversion was greater in green parts of plants, such as leaves and stem, than in underground parts of potato plants. Nicotinic acid utilised for the biosynthesis of these conjugates seems to be derived not only from the pyridine nucleotide cycle, but also from the de novo synthesis of nicotinic acid mononucleotide.

Calcite crystal growth rate inhibition by polycarboxylic acids

USGS Publications Warehouse

Reddy, M.M.; Hoch, A.R.

2001-01-01

Calcite crystal growth rates measured in the presence of several polycarboxyclic acids show that tetrahydrofurantetracarboxylic acid (THFTCA) and cyclopentanetetracarboxylic acid (CPTCA) are effective growth rate inhibitors at low solution concentrations (0.01 to 1 mg/L). In contrast, linear polycarbocylic acids (citric acid and tricarballylic acid) had no inhibiting effect on calcite growth rates at concentrations up to 10 mg/L. Calcite crystal growth rate inhibition by cyclic polycarboxyclic acids appears to involve blockage of crystal growth sites on the mineral surface by several carboxylate groups. Growth morphology varied for growth in the absence and in the presence of both THFTCA and CPTCA. More effective growth rate reduction by CPTCA relative to THFTCA suggests that inhibitor carboxylate stereochemical orientation controls calcite surface interaction with carboxylate inhibitors. ?? 20O1 Academic Press.

Occurrence of carboxylic acids in different steps of two drinking-water treatment plants using different disinfectants.

PubMed

Jurado-Sánchez, Beatriz; Ballesteros, Evaristo; Gallego, Mercedes

2014-03-15

The occurrence of 35 aliphatic and aromatic carboxylic acids within two full scale drinking-water treatment plants was evaluated for the first time in this research. At the intake of each plant (raw water), the occurrence of carboxylic acids varied according to the quality of the water source although in both cases 13 acids were detected at average concentrations of 6.9 and 4.7 μg/L (in winter). In the following steps in each treatment plant, the concentration patterns of these compounds differed depending on the type of disinfectant applied. Thus, after disinfection by chloramination, the levels of the acids remained almost constant (average concentration, 6.3 μg/L) and four new acids were formed (butyric, 2-methylbutyric, 3-hydroxybenzoic and 2-nitrobenzoic) at low levels (1.1-5 μg/L). When ozonation/chlorination was used, the total concentration of the carboxylic acids in the raw water sample (4.7 μg/L) increased up to 6 times (average concentration, 26.3 μg/L) after disinfection and 6 new acids (mainly aromatic) were produced at high levels (3.5-100 μg/L). Seasonal variations of the carboxylic acids under study showed that in both plants, maximum levels of all the analytes were reached in the coldest months (autumn and winter), aromatic acids only being found in those seasons. Copyright © 2013 Elsevier Ltd. All rights reserved.

Multiple forms of statherin in human salivary secretions.

PubMed

Jensen, J L; Lamkin, M S; Troxler, R F; Oppenheim, F G

1991-01-01

Sequential chromatography of hydroxyapatite-adsorbed salivary proteins from submandibular/sublingual secretions on Sephadex G-50 and reversed-phase HPLC resulted in the purification of statherin and several statherin variants. Amino acid analysis, Edman degradation and carboxypeptidase digestion of the obtained protein fractions led to the determination of the complete primary structures of statherin SV1, statherin SV2, and statherin SV3. SV1 is identical to statherin but lacks the carboxyl-terminal phenylalanine residue. SV2, lacking residues 6-15, is otherwise identical to statherin. SV3 is identical to SV2 but lacks the carboxyl-terminal phenylalanine. These results provide the first evidence for multiple forms of statherin which are probably derived both by post-translational modification and alternative splicing of the statherin gene.

Zwitterionic metal carboxylate complexes: In solid state

NASA Astrophysics Data System (ADS)

Nath, Bhaskar; Kalita, Dipjyoti; Baruah, Jubaraj B.

2012-07-01

A flexible dicarboxylic acid having composition [(CH(o-C5H4N)(p-C6H4OCH2CO2H)2] derived from corresponding bis-phenol reacts with various metal(II) acetates such as manganese(II), cobalt(II) and nickel(II) acetate leads to zwtterionic complexes with compositions [CH(o-C5H4N)(p-C6H4OCH2CO2){p-C6H4OCH2CO2M(H2O)5}].6H2O (where M = Mn, Co, Ni). The complexes are characterised by X-ray crystallography. These complexes have chiral center due to unsymmetric structure conferred to the ligand through coordination at only one carboxylate group of the ligand. In solid state these complexes are racemic.

Antitumor activity of newly synthesized oxo and ethylidene derivatives of bile acids and their amides and oxazolines.

PubMed

Bjedov, Srđan; Jakimov, Dimitar; Pilipović, Ana; Poša, Mihalj; Sakač, Marija

2017-04-01

Bile acid derivatives with modifications in side chain and modifications on steroid skeleton were synthetized and their antitumor activity against five human cancer cell lines was investigated. Modifications in side chain include amid group, formed in reaction with 2-amino-2-methylpropanol, and 4,4-dimethyloxazoline group, obtained after cyclization of amides. In the steroid skeleton oxo groups were introduced in position 7 (2, 2a, 2b) and 7,12 (3, 3a, 3b). Ethylidene groups were introduced regio- and stereoselectively on C-7, and/or without stereoselectivity on C-3 by Wittig reaction. By combination of these modifications, a series of 19 bile acid derivatives were synthesized. Compounds containing both C-7 ethylidene and C-12 carbonyl groups (6, 6a, 6b) shown very good antitumor activity with IC 50 <5µM. Altering carboxylic group to amide or oxazoline group has positive effect on cytotoxicity. Different molecular descriptors were determined in silico and after principal component analysis was found that molecular descriptor BLTF96 can be used for fast assessment of experimental cytotoxicity of bile acid derivatives. Copyright © 2017 Elsevier Inc. All rights reserved.

Click strategy using disodium salts of amino acids improves the water solubility of plinabulin and KPU-300.

PubMed

Yakushiji, Fumika; Muguruma, Kyohei; Hayashi, Yoshiki; Shirasaka, Takuya; Kawamata, Ryosuke; Tanaka, Hironari; Yoshiwaka, Yushi; Taguchi, Akihiro; Takayama, Kentaro; Hayashi, Yoshio

2017-07-15

Plinabulin and KPU-300 are promising anti-microtubule agents; however, the low water solubility of these compounds (<0.1µg/mL) has limited their pharmaceutical advantages. Here, we developed five water-soluble derivatives of plinabulin and KPU-300 with a click strategy using disodium salts of amino acids. The mother skeleton, diketopiperazine (DKP), was transformed into a monolactim-type alkyne and a copper-catalyzed alkyne azide cycloaddition (CuAAC) combined azides that was derived from amino acids as a water-solubilizing moiety. The conversion of carboxyl groups into disodium salts greatly improved the water solubility by 0.8 million times compared to the solubility of the parent molecules. In addition, the α-amino acid side chains of the water-solubilizing moieties affected both the water solubility and the half-lives of the compounds during enzymatic hydrolysis. Our effort to develop a variety of water-soluble derivatives using the click strategy has revealed that the replaceable water-solubilizing moieties can alter molecular solubility and stability under enzymatic hydrolysis. With this flexibility, we are approaching to the in vivo study using water-soluble derivative. Copyright © 2017 Elsevier Ltd. All rights reserved.

A chromene and prenylated benzoic acid from Piper aduncum.

PubMed

Baldoqui, D C; Kato, M J; Cavalheiro, A J; Bolzani, V da S; Young, M C; Furlan, M

1999-08-01

In addition to nerolidol, 2',6'-dihydroxy-4'-methoxydihydrochalcone, methyl 2,2-dimethyl-8-(3'-methyl-2'-butenyl)-2H-1-chromene-6-carboxylate, methyl 2,2-dimethyl-2H-1-chromene-6-carboxylate and methyl 8-hydroxy-2,2-dimethyl-2H-1-chromene-6-carboxylate, two new natural products were isolated from the leaves of Piper aduncum, 2,2-dimethyl-2H-1-chromene-6-carboxylic acid and 3-(3',7'-dimethyl-2',6'-octadienyl)-4-methoxybenzoic acid. The structures of the isolates were established based on analysis of spectroscopic data, including ES-MS. The DNA-damaging activity of the isolated compounds was also investigated against mutant strains of Saccharomyces cerevisiae.

Environmentally benign graphite intercalation compound composition for exfoliated graphite, flexible graphite, and nano-scaled graphene platelets

DOEpatents

Zhamu, Aruna; Jang, Bor Z.

2014-06-17

A carboxylic-intercalated graphite compound composition for the production of exfoliated graphite, flexible graphite, or nano-scaled graphene platelets. The composition comprises a layered graphite with interlayer spaces or interstices and a carboxylic acid residing in at least one of the interstices, wherein the composition is prepared by a chemical oxidation reaction which uses a combination of a carboxylic acid and hydrogen peroxide as an intercalate source. Alternatively, the composition may be prepared by an electrochemical reaction, which uses a carboxylic acid as both an electrolyte and an intercalate source. Exfoliation of the invented composition does not release undesirable chemical contaminants into air or drainage.

One-step hydrothermal synthesis of carboxyl-functionalized upconversion phosphors for bioapplications.

PubMed

Yang, Jianping; Shen, Dengke; Li, Xiaomin; Li, Wei; Fang, Yin; Wei, Yong; Yao, Chi; Tu, Bo; Zhang, Fan; Zhao, Dongyuan

2012-10-22

In this paper, we report a facile one-step hydrothermal method to synthesize phase-, size-, and shape-controlled carboxyl-functionalized rare-earth fluorescence upconversion phosphors by using a small-molecule binary acid, such as malonic acid, oxalic acid, succinic acid, or tartaric acid as capping agent. The crystals, from nano- to microstructures with diverse shapes that include nanospheres, microrods, hexagonal prisms, microtubes, microdisks, polygonal columns, and hexagonal tablets, can be obtained with different reaction times, reaction temperatures, molar ratios of capping agent to sodium hydroxide, and by varying the binary acids. Fourier transform infrared, thermogravimetric analysis, and upconversion luminescence spectra measurements indicate that the synthesized NaYF(4):Yb/Er products with hydrophilic carboxyl-functionalized surface offer efficient upconversion luminescent performance. Furthermore, the antibody/secondary antibody conjugation can be realized by the carboxyl-functionalized surfaces of the upconversion phosphors, thus indicating the potential bioapplications of these kinds of materials. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Carbon-Carbon Bond Formation and Hydrogen Production in the Ketonization of Aldehydes.

PubMed

Orozco, Lina M; Renz, Michael; Corma, Avelino

2016-09-08

Aldehydes possess relatively high chemical energy, which is the driving force for disproportionation reactions such as Cannizzaro and Tishchenko reactions. Generally, this energy is wasted if aldehydes are transformed into carboxylic acids with a sacrificial oxidant. Here, we describe a cascade reaction in which the surplus energy of the transformation is liberated as molecular hydrogen for the oxidation of heptanal to heptanoic acid by water, and the carboxylic acid is transformed into potentially industrially relevant symmetrical ketones by ketonic decarboxylation. The cascade reaction is catalyzed by monoclinic zirconium oxide (m-ZrO2 ). The reaction mechanism has been studied through cross-coupling experiments between different aldehydes and acids, and the final symmetrical ketones are formed by a reaction pathway that involves the previously formed carboxylic acids. Isotopic studies indicate that the carboxylic acid can be formed by a hydride shift from the adsorbed aldehyde on the metal oxide surface in the absence of noble metals. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Vitamin K catabolite inhibition of ovariectomy-induced bone loss: structure-activity relationship considerations.

PubMed

Soper, Robin J; Oguz, Cenk; Emery, Roger; Pitsillides, Andrew A; Hodges, Stephen J

2014-08-01

The potential benefit of vitamin K as a therapeutic in osteoporosis is controversial and the vitamin K regimen being used clinically (45 mg/day) employs doses that are many times higher than required to ensure maximal gamma-carboxylation of the vitamin K-dependent bone proteins. We therefore tested the hypothesis that vitamin K catabolites, 5-carbon (CAN5C) and 7-carbon carboxylic acid (CAN7C) aliphatic side-chain derivatives of the naphthoquinone moiety exert an osteotrophic role consistent with the treatment of osteoporosis. Osteoblast-like MG63 cell cultures were challenged with lipopolysaccharide and the levels of interleukin-6, an osteoclastogenic cytokine, measured with and without catabolites; low concentrations of CAN7C significantly inhibited interleukin-6 release, but CAN5C did not. In models of bone loss induced by ovariectomy or sciatic neurectomy in C57BL/6 mice, we found that the rarer CAN7C catabolite markedly restricted ovariectomy-induced bone loss and possibly limited sciatic neurectomy-induced bone loss. CAN7C activity depends on a free carboxylic acid and its particular side-chain structure. These in vivo data indicate for the first time that the clinical utility of vitamin K for osteoporosis may reside in an unusual catabolite. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and antitumour activity of 4-aminoquinazoline derivatives

NASA Astrophysics Data System (ADS)

Lipunova, G. N.; Nosova, E. V.; Charushin, V. N.; Chupakhin, O. N.

2016-07-01

Pieces of data on the synthesis and antitumour activity of 4-aminoquinazolines are summarized and analyzed. Key methods for the synthesis of these compounds are considered, primarily cyclocondensation of carboxylic acid derivatives, as well as the oxidation of quinazolines and the cyclization of disubstituted thioureas. Improvements of synthetic schemes for erlotinib, gefitinib and lapatinib, which are the best-known pharmaceuticals based on compounds of the title class, are also considered. Synthetic strategies and biological activities for new 4-aminoquinazoline derivatives that are EGFR-tyrosine kinase inhibitors, multiactive compounds, and labelled compounds for use as positron emission tomography (PET) imaging agents are discussed. The bibliography includes 263 references.

Carboxylated hyperbranched poly(glycidol)s for preparation of pH-sensitive liposomes.

PubMed

Yuba, Eiji; Harada, Atsushi; Sakanishi, Yuichi; Kono, Kenji

2011-01-05

Previous reports by the authors described intracellular delivery using liposomes modified with various carboxylated poly(glycidol) derivatives. These linear polymer-modified liposomes exhibited a pH-dependent membrane fusion behavior in cellular acidic compartments. However, the effect of the backbone structure on membrane fusion activity remains unknown. Therefore, this study specifically investigated the backbone structure to obtain pH-sensitive polymers with much higher fusogenic activity and to reveal the effect of the polymer backbone structure on the interaction with the membrane. Hyperbranched poly(glycidol) (HPG) derivatives were prepared as a new type of pH-sensitive polymer and used for the modification of liposomes. The resultant HPG derivatives exhibited high hydrophobicity and intensive interaction with the membrane concomitantly with the increasing degree of polymerization (DP). Furthermore, HPG derivatives showed a stronger interaction with the membrane than the linear polymers show. Liposomes modified with HPG derivatives of high DP delivered contents into the cytosol of DC2.4 cells, a dendritic cell line, more effectively than the linear polymer-modified liposomes do. Results show that the backbone structure of pH-sensitive polymers affected their pH-sensitivity and interaction with liposomal and cellular membranes. Copyright © 2010 Elsevier B.V. All rights reserved.

Calcite crystal growth inhibition by humic substances with emphasis on hydrophobic acids from the Florida Everglades

USGS Publications Warehouse

Hoch, A.R.; Reddy, M.M.; Aiken, G.R.

2000-01-01

The crystallization of calcium carbonate minerals plays an integral role in the water chemistry of terrestrial ecosystems. Humic substances, which are ubiquitous in natural waters, have been shown to reduce or inhibit calcite crystal growth in experiments. The purpose of this study is to quantify and understand the kinetic effects of hydrophobic organic acids isolated from the Florida Everglades and a fulvic acid from Lake Fryxell, Antarctica, on the crystal growth of calcite (CaCO3). Highly reproducible calcite growth experiments were performed in a sealed reactor at constant pH, temperature, supersaturation (?? = 4.5), P(CO2) (10-3.5atm), and ionic strength (0.1 M) with various concentrations of organic acids. Higher plant-derived aquatic hydrophobic acids from the Everglades were more effective growth inhibitors than microbially derived fulvic acid from Lake Fryxell. Organic acid aromaticity correlated strongly with growth inhibition. Molecular weight and heteroatom content correlated well with growth inhibition, whereas carboxyl content and aliphatic nature did not. Copyright (C) 1999 Elsevier Science Ltd.

Crystal structure and ligand affinity of avidin in the complex with 4‧-hydroxyazobenzene-2-carboxylic acid

NASA Astrophysics Data System (ADS)

Strzelczyk, Paweł; Bujacz, Grzegorz

2016-04-01

Avidin is a protein found in egg white that binds numerous organic compounds with high affinity, especially biotin and its derivatives. Due to its extraordinary affinity for its ligands, avidin is extensively used in biotechnology. X-ray crystallography and fluorescence-based biophysical techniques were used to show that avidin binds the dye 4‧-hydroxyazobenzene-2-carboxylic acid (HABA) with a lower affinity than biotin. The apparent dissociation constant determined for the avidin complex with HABA by microscale thermophoresis (MST) is 4.12 μM. The crystal structure of avidin-HABA complex was determined at a resolution of 2.2 Å (PDB entry 5chk). The crystals belong to a hexagonal system, in the space group P6422. In that structure, the hydrazone tautomer of HABA is bound at the bottom part of the central calyx near the polar residues. We show interactions of the dye with avidin and compare them with the previously reported avidin-biotin complex.

Jasmonate signaling in plant stress responses and development - active and inactive compounds.

PubMed

Wasternack, Claus; Strnad, Miroslav

2016-09-25

Jasmonates (JAs) are lipid-derived signals mediating plant responses to biotic and abiotic stresses and in plant development. Following the elucidation of each step in their biosynthesis and the important components of perception and signaling, several activators, repressors and co-repressors have been identified which contribute to fine-tuning the regulation of JA-induced gene expression. Many of the metabolic reactions in which JA participates, such as conjugation with amino acids, glucosylation, hydroxylation, carboxylation, sulfation and methylation, lead to numerous compounds with different biological activities. These metabolites may be highly active, partially active in specific processes or inactive. Hydroxylation, carboxylation and sulfation inactivate JA signaling. The precursor of JA biosynthesis, 12-oxo-phytodienoic acid (OPDA), has been identified as a JA-independent signaling compound. An increasing number of OPDA-specific processes is being identified. To conclude, the numerous JA compounds and their different modes of action allow plants to respond specifically and flexibly to alterations in the environment. Copyright © 2015 Elsevier B.V. All rights reserved.

Cytotoxic effects of polybasic acids, poly(alkenoic acid)s, and the monomers with various functional groups on human pulp fibroblasts.

PubMed

Kurata, Shigeaki; Morishita, Kumiko; Kawase, Toshio; Umemoto, Kozo

2011-01-01

This study evaluated the cytotoxicity of various polybasic acids, poly(alkenoic acid)s, and the monomers with various acidic functional groups such as carboxyl, phosphoryl, and sulfo group. The cell growth of fibroblasts cultivated in medium containing polybasic acids and polymers up to the concentration to 5 mmol/L was not significantly different compared with that of control without their acids. On the other hand, the cell growth fibroblasts cultivated in medium containing 1 mmol/L of the monomers with acryloyloxy and phosphoryl or carboxyl group decreased remarkably compared with that of the control and the cells were probably lifeless. Those exposed to the monomers with a ether bond and a carboxyl group or a amide bond and a sulfo group was not significantly different compared with that of control.

Where and What Is Pristine Marine Aerosol?

NASA Astrophysics Data System (ADS)

Russell, L. M.; Frossard, A. A.; Long, M. S.; Burrows, S. M.; Elliott, S.; Bates, T. S.; Quinn, P.

2014-12-01

The sources and composition of atmospheric marine aerosol particles have been measured by functional group composition (from Fourier transform infrared spectroscopy) to identify the organic composition of the pristine primary marine (ocean-derived) particles as 65% hydroxyl, 21% alkane, 6% amine, and 7% carboxylic acid functional groups [Frossard et al., 2014a,b]. Pristine but non-primary components from photochemical reactions (likely from biogenic marine vapor emissions) add carboxylic acid groups. Non-pristine contributions include shipping effluent in seawater and ship emissions, which add additional alkane groups (up to 70%), and coastal or continental emissions mix in alkane and carboxylic acid groups. The pristine primary marine (ocean-derived) organic aerosol composition is nearly identical to model generated primary marine aerosol particles from bubbled seawater, indicating that its overall functional group composition is the direct consequence of the organic constituents of the seawater source. While the seawater organic functional group composition was nearly invariant across all three ocean regions studied and the ratio of organic carbon to sodium (OC/Na+) in the generated primary marine aerosol particles remained nearly constant over a broad range of chlorophyll-a concentrations, the generated primary marine aerosol particle alkane group fraction increased with chlorophyll-a concentrations. In addition, the generated primary marine aerosol particles have a hydroxyl group absorption peak location characteristic of monosaccharides and disaccharides, where the seawater hydroxyl group peak location is closer to that of polysaccharides. References Cited Frossard, Amanda A., Lynn M. Russell, Paola Massoli, Timothy S. Bates, and Patricia K. Quinn, "Side-by-Side Comparison of Four Techniques Explains the Apparent Differences in the Organic Composition of Generated and Ambient Marine Aerosol Particles," Aerosol Science and Technology - Aerosol Research Letter, 48:v-x, doi10.1080/02786826.2013.879979, 2014a. Frossard, A.A., L.M. Russell, M.S. Long, S.M. Burrows, S.M. Elliot, T.S. Bates, and P.K. Quinn, "Sources and Composition of Submicron Organic Mass in Marine Aerosol Particles," Journal of Geophysical Research - Atmospheres, submitted 2014b.

Novel Lactate Transporters from Carboxylic Acid-Producing Rhizopus

USDA-ARS?s Scientific Manuscript database

The fungus Rhizopus is frequently used for fermentative production of lactic acid, but little is known about the mechanisms or proteins for transporting this carboxylic acid. Since transport of the lactate anion across the plasma membrane is critical to prevent acidification of the cytoplasm, we ev...

Transcriptomic Analysis of Carboxylic Acid Challenge in Escherichia coli: Beyond Membrane Damage

PubMed Central

Royce, Liam A.; Boggess, Erin; Fu, Yao; Liu, Ping; Shanks, Jacqueline V.; Dickerson, Julie; Jarboe, Laura R.

2014-01-01

Carboxylic acids are an attractive biorenewable chemical. Enormous progress has been made in engineering microbes for production of these compounds though titers remain lower than desired. Here we used transcriptome analysis of Escherichia coli during exogenous challenge with octanoic acid (C8) at pH 7.0 to probe mechanisms of toxicity. This analysis highlights the intracellular acidification and membrane damage caused by C8 challenge. Network component analysis identified transcription factors with altered activity including GadE, the activator of the glutamate-dependent acid resistance system (AR2) and Lrp, the amino acid biosynthesis regulator. The intracellular acidification was quantified during exogenous challenge, but was not observed in a carboxylic acid producing strain, though this may be due to lower titers than those used in our exogenous challenge studies. We developed a framework for predicting the proton motive force during adaptation to strong inorganic acids and carboxylic acids. This model predicts that inorganic acid challenge is mitigated by cation accumulation, but that carboxylic acid challenge inverts the proton motive force and requires anion accumulation. Utilization of native acid resistance systems was not useful in terms of supporting growth or alleviating intracellular acidification. AR2 was found to be non-functional, possibly due to membrane damage. We proposed that interaction of Lrp and C8 resulted in repression of amino acid biosynthesis. However, this hypothesis was not supported by perturbation of lrp expression or amino acid supplementation. E. coli strains were also engineered for altered cyclopropane fatty acid content in the membrane, which had a dramatic effect on membrane properties, though C8 tolerance was not increased. We conclude that achieving higher production titers requires circumventing the membrane damage. As higher titers are achieved, acidification may become problematic. PMID:24586888

Modeling the partitioning of organic chemical species in cloud phases with CLEPS (1.1)

NASA Astrophysics Data System (ADS)

Rose, Clémence; Chaumerliac, Nadine; Deguillaume, Laurent; Perroux, Hélène; Mouchel-Vallon, Camille; Leriche, Maud; Patryl, Luc; Armand, Patrick

2018-02-01

The new detailed aqueous-phase mechanism Cloud Explicit Physico-chemical Scheme (CLEPS 1.0), which describes the oxidation of isoprene-derived water-soluble organic compounds, is coupled with a warm microphysical module simulating the activation of aerosol particles into cloud droplets. CLEPS 1.0 was then extended to CLEPS 1.1 to include the chemistry of the newly added dicarboxylic acids dissolved from the particulate phase. The resulting coupled model allows the prediction of the aqueous-phase concentrations of chemical compounds originating from particle scavenging, mass transfer from the gas-phase and in-cloud aqueous chemical reactivity. The aim of the present study was more particularly to investigate the effect of particle scavenging on cloud chemistry. Several simulations were performed to assess the influence of various parameters on model predictions and to interpret long-term measurements conducted at the top of Puy de Dôme (PUY, France) in marine air masses. Specific attention was paid to carboxylic acids, whose predicted concentrations are on average in the lower range of the observations, with the exception of formic acid, which is rather overestimated in the model. The different sensitivity runs highlight the fact that formic and acetic acids mainly originate from the gas phase and have highly variable aqueous-phase reactivity depending on the cloud acidity, whereas C3-C4 carboxylic acids mainly originate from the particulate phase and are supersaturated in the cloud.

In vivo assessment of parenteral formulations of oligo(3-hydroxybutyric Acid) conjugates with the model compound Ibuprofen.

PubMed

Stasiak, Pawel; Sznitowska, Malgorzata; Ehrhardt, Carsten; Luczyk-Juzwa, Maria; Grieb, Pawel

2010-12-01

Polymer-drug conjugates have gained significant attention as pro-drugs releasing an active substance as a result of enzymatic hydrolysis in physiological environment. In this study, a conjugate of 3-hydroxybutyric acid oligomers with a carboxylic acid group-bearing model drug (ibuprofen) was evaluated in vivo as a potential pro-drug for parenteral administration. Two different formulations, an oily solution and an o/w emulsion were prepared and administered intramuscularly (IM) to rabbits in a dose corresponding to 40 mg of ibuprofen/kilogramme. The concentration of ibuprofen in blood plasma was analysed by HPLC, following solid-phase extraction and using indometacin as internal standard (detection limit, 0.05 microg/ml). No significant differences in the pharmacokinetic parameters (C (max), T (max), AUC) were observed between the two tested formulations of the 3-hydroxybutyric acid conjugate. In comparison to the non-conjugated drug in oily solution, the relative bioavailability of ibuprofen conjugates from oily solution, and o/w emulsion was reduced to 17% and 10%, respectively. The 3-hydroxybutyric acid formulations released the active substance over a significantly extended period of time with ibuprofen still being detectable 24 h post-injection, whereas the free compound was almost completely eliminated as early as 6 h after administration. The conjugates remained in a muscle tissue for a prolonged time and can hence be considered as sustained release systems for carboxylic acid derivatives.

Synthesis and biological evaluation of naphthyldesferrithiocin iron chelators.

PubMed

Bergeron, R J; Wiegand, J; Wollenweber, M; McManis, J S; Algee, S E; Ratliff-Thompson, K

1996-04-12

The synthesis and iron-clearing properties of the naphthyldesferrithiocins 2-(2'-hydroxynaphth-1'-yl)-delta2-thiazoline-(4R)-carboxylic acid, 2-(2'-hydroxynaphth-1'-yl)-delta2-thiazoline-(4S)-carboxylic acid, 2-(3'-hydroxynaphth-2'-yl)-delta2-thiazoline-(4R)-carboxylic acid, and 2-(3'-hydroxynaphth-2'-yl)-delta2-thiazoline-(4S)-carboxylic acid are described. While the bile duct-cannulated rat model clearly demonstrates that the 3'-hydroxynaphthyl-2'-yl compounds are orally active iron-clearing agents and the corresponding 2'-hydroxynaphthyl-1'-yl compounds are not, in the primate model none of the benz-fused desazadesferrithiocin analogues are active. Oral versus subcutaneous administration of these ligands strongly suggests that metabolism is a key issue in their iron-clearing properties and that these benz-fused desferrithiocins are not good candidates for orally active iron-clearing drugs.

Extraction of ethanol with higher carboxylic acid solvents and their toxicity to yeast

USDA-ARS?s Scientific Manuscript database

In a screening exercise for ethanol-selective extraction solvents, partitioning of ethanol and water from a 5 wt% aqueous solution into several C8 – C18 carboxylic acids was studied. Results for the acids are compared with those from alcohols of similar structure. In all cases studied, the acids exh...

Synthesis and biological evaluation of some N-(3-(1H-tetrazol-5-yl) phenyl)acetamide derivatives as novel non-carboxylic PTP1B inhibitors designed through bioisosteric modulation.

PubMed

Maheshwari, Neelesh; Karthikeyan, Chandrabose; Bhadada, Shraddha V; Sahi, Chandan; Verma, Amit K; Hari Narayana Moorthy, N S; Trivedi, Piyush

2018-06-08

Described herein is the synthesis and biological evaluation of a series of non-carboxylic inhibitors of Protein Tyrosine Phosphatase 1B designed using bioisosteric replacement strategy. Six N-(3-(1H-tetrazol-5-yl)phenyl)acetamide derivatives designed employing the aforementioned strategy were synthesized and screened for PTP1B inhibitory activity. Among the synthesized compounds, compound NM-03 exhibited the most potent inhibitory activity with IC 50 value of 4.48 µM. Docking studies with NM-03 revealed the key interactions with desired amino acids in the binding site of PTP1B. Furthermore, compound NM-03 also elicited good in vivo activity. Taken together, the results of this study establish N-(3-(1H-tetrazole-5-yl)phenyl)-2-(benzo[d]oxazol-2-ylthio)acetamide (NM-03) as a valuable lead molecule with great potential for PTP1B inhibitor development targeting diabetes. Copyright © 2018 Elsevier Inc. All rights reserved.

Characterization of a dual specificity aryl acid adenylation enzyme with dual function in nikkomycin biosynthesis.

PubMed

Moon, Mary; Van Lanen, Steven G

2010-09-01

Nikkomycin Z is a dipeptide antifungal antibiotic characterized by two nonproteinogenic amino acids, nikkomycin C(Z) and 4-(4'-hydroxy-2'-pyridinyl)-homothreonine (HPHT). The HPHT scaffold is assembled by an aldol reaction between 2-oxobutyrate and picolinaldehyde, the latter of which is derived from picolinic acid that is activated and loaded to coenzyme A by the aryl-activating adenylation enzyme, NikE. We now provide evidence that NikE is also involved in the activation and loading of the alpha-keto acid precursor, 4-(2'-pyridinyl)-2-oxo-4-hydroxyisovalerate (POHIV), to a phosphopantetheinyl group of an acyl carrier protein domain of NikT. POHIV was synthesized using Escherichia coli 2-dehydro-3-deoxy-phosphogluconate aldolase, and phenylalanine dehydrogenase from Bacillus sp. NRRL B-14911 was used to prepare the alpha-amino acid, 4-(2'-pyridinyl)-homothreonine (PHT). Using the carboxylic acid-dependent, ATP-[(32)P]PP(i) exchange assay, NikE is shown to activate both picolinic acid and POHIV but not PHT. Furthermore, NikE loads POHIV to holo-NikT to generate a new thioester-linked intermediate, which was not observed using a NikT(S33A) mutant. Thus, NikE activates two distinct carboxylic acids to form two new thioester intermediates, one of which is subsequently reduced to the aldehyde and the other that likely serves as a substrate for the aminotransferase domain of NikT prior to condensation with nikkomycin C(Z) to yield the dipeptide. Copyright 2010 Wiley Periodicals, Inc.

Antagonistic Activity and Mode of Action of Phenazine-1-Carboxylic Acid, Produced by Marine Bacterium Pseudomonas aeruginosa PA31x, Against Vibrio anguillarum In vitro and in a Zebrafish In vivo Model

PubMed Central

Zhang, Linlin; Tian, Xueying; Kuang, Shan; Liu, Ge; Zhang, Chengsheng; Sun, Chaomin

2017-01-01

Phenazine and its derivatives are very important secondary metabolites produced from Pseudomonas spp. and have exhibited broad-spectrum antifungal and antibacterial activities. However, till date, there are few reports about marine derived Pseudomonas and its production of phenazine metabolites. In this study, we isolated a marine Pseudomonas aeruginosa strain PA31x which produced natural product inhibiting the growth of Vibrio anguillarum C312, one of the most serious bacterial pathogens in marine aquaculture. Combining high-resolution electro-spray-ionization mass spectroscopy and nuclear magnetic resonance spectroscopy analyses, the functional compound against V. anguillarum was demonstrated to be phenazine-1-carboxylic acid (PCA), an important phenazine derivative. Molecular studies indicated that the production of PCA by P. aeruginosa PA31x was determined by gene clusters phz1 and phz2 in its genome. Electron microscopic results showed that treatment of V. anguillarum with PCA developed complete lysis of bacterial cells with fragmented cytoplasm being released to the surrounding environment. Additional evidence indicated that reactive oxygen species generation preceded PCA-induced microbe and cancer cell death. Notably, treatment with PCA gave highly significant protective activities against the development of V. anguillarum C312 on zebrafish. Additionally, the marine derived PCA was further found to effectively inhibit the growth of agricultural pathogens, Acidovorax citrulli NP1 and Phytophthora nicotianae JM1. Taken together, this study reveals that marine Pseudomonas derived PCA carries antagonistic activities against both aquacultural and agricultural pathogens, which broadens the application fields of PCA. PMID:28289406

A gadolinium(III) complex of a carboxylic-phosphorus acid derivative of diethylenetriamine covalently bound to inulin, a potential macromolecular MRI contrast agent.

PubMed

Lebdusková, Petra; Kotek, Jan; Hermann, Petr; Vander Elst, Luce; Muller, Robert N; Lukes, Ivan; Peters, Joop A

2004-01-01

A novel conjugate of a polysaccharide and a Gd(III) chelate with potential as contrast agent for magnetic resonance imaging (MRI) was synthesized. The structure of the chelate was derived from H5DTPA by replacing the central pendant arm by a phosphinic acid functional group, which was covalently bound to the polysaccharide inulin. On the average, each monosaccharide unit of the inulin was attached to approximately one (0.9) chelate moiety. The average molecular weight is 23110 and the average number of Gd3+ ions per molecule is 24. The ligand binds the Gd3+ ion in an octadentate fashion via three nitrogen atoms, four carboxylate oxygen atoms, and one P-O oxygen atom, and its first coordination sphere is completed by a water molecule. This compound shows promising properties for application as a contrast agent for MRI thanks to a favorable residence lifetime of this water molecule (170 ns at 298 K), a relatively long rotational correlation time (866 ps at 298 K), and the presence of two water molecules in the second coordination sphere of the Gd3+ ion. Furthermore, its stability toward transmetalation with Zn(II) is as high as that of the clinically used [Gd(DTPA)(H2O)]2-.

Synthesis and Bioactivity Evaluation of Novel 2-Salicyloylbenzofurans as Antibacterial Agents.

PubMed

Phan, Phuong-Thuy T; Nguyen, Thu-Trang T; Nguyen, Hong-Nhung T; Le, Bao-Khanh N; Vu, Thao T; Tran, Dong C; Pham, Tuan-Anh N

2017-04-25

In order to discover new antibacterial agents, series of 2-salicyloylbenzofuran derivatives were designed, synthesized and evaluated for their antibacterial activities against three Gram-(+) strains (methicillin-sensitive Staphylococcus aureus (MSSA) ATCC 29213, methicillin-resistant Staphylococcus aureus (MRSA) ATCC 43300, and Streptococcus faecalis ( S. faecalis ) ATCC 29212) and one Gram-(-) strain ( Escherichia coli (E. coli) ATCC 25922). The 2-salicyloylbenzofuran heterocycles were generated by Rap-Stoermer condensation of salicylaldehydes with phenacyl bromides and then converted to diverse O -ether derivatives by Williamson synthesis. The targeted products were screened for in vitro qualitative (zone of inhibition) and quantitative (MIC) antibacterial activities by agar well diffusion assay and agar dilution method. Amongst the compounds, those bearing carboxylic acid functional group were found to exhibit reasonable activity against Gram-(+) bacterial strains including S. faecalis , MSSA and MRSA with the most potent antibacterial agent 8h (MICs = 0.06-0.12 mM). Besides, the 2-salicyloylbenzofurans partly displayed inhibitory activity against MRSA with the best MICs = 0.14 mM ( 8f ) and 0.12 mM ( 8h ). Finally, the antibacterial results preliminarily suggested that the substituent bearing carboxylic acid group at salicyloyl-C2 and the bromine atoms on the benzofuran moiety seem to be the functionality necessary for antibacterial activities.

Isolation and characterization of mammalian eumelanins from hair and irides.

PubMed

Novellino, L; Napolitano, A; Prota, G

2000-07-26

A new enzymatic procedure was developed for isolation of eumelanin from black human hair which might provide a substantially intact pigment for structural characterization. Sequential digestion with protease, proteinase K and papaine in the presence of dithiothreitol afforded a pigment with a 6% w/w protein content. HPLC analysis of pyrrole acids resulting from alkaline H(2)O(2) degradation, carboxyl content determination, and ferricyanide titration showed that the isolated pigment is made up of 5,6-dihydroxyindole (DHI)- and 5, 6-dihydroxyindole-2-carboxylic acid (DHICA)-derived units at a 6:1 ratio, exhibiting a significant degree of oxidative degradation. For comparison, a different eumelanin isolated from black bovine irides by a similar enzymatic procedure was analyzed. Matrix-assisted laser desorption ionization (MALDI) mass spectrometry of the final pigment provided evidence for homologous series of DHICA oligomers, while chemical analysis allowed an estimate of 2:1 DHICA/DHI-derived units in the polymer, with a substantial proportion of intact o-diphenolic functions. Iris melanin proved able to promote the Fenton oxidation of deoxyribose while hair melanin was ineffective. Overall, these results provide, for the first time, unambiguous evidence for marked structural differences of mammalian eumelanins which may be directly related to the diversity of the sites of biosynthesis and storage, as well as to functional role of these pigments.

Revised structure for the phenazine antibiotic from Pseudomonas fluorescens 2-79 (NRRL B-15132).

PubMed Central

Brisbane, P G; Janik, L J; Tate, M E; Warren, R F

1987-01-01

A phenazine antibiotic (mp, 243 to 244 degrees C), isolated in a yield of 134 micrograms/ml from cultures of Pseudomonas fluorescens 2-79 (NRRL B-15132), was indistinguishable in all of its measured physicochemical (melting point, UV and infrared spectra, and gas chromatography-mass spectrometry data) and biological properties from synthetic phenazine-1-carboxylic acid. Gurusiddaiah et al. (S. Gurusiddaiah, D. M. Weller, A. Sarkar, and R. J. Cook, Antimicrob. Agents Chemother. 29:488-495, 1986) attributed a dimeric phenazine structure to an antibiotic with demonstrably similar properties obtained from the same bacterial strain. Direct comparison of the physicochemical properties of the authentic antibiotic obtained from D. M. Weller with synthetic phenazine-1-carboxylic acid and with the natural product from the present study established that all three samples were indistinguishable within the experimental error of each method. No evidence to support the existence of a biologically active dimeric species was obtained. Phenazine-1-carboxylic acid has a pKa of 4.24 +/- 0.01 (25 degrees C; I = 0.09), and its carboxylate anion shows no detectable antimicrobial activity compared with the active uncharged carboxylic acid species. These data suggest that phenazine-1-carboxylic acid is probably not an effective biological control agent for phytopathogens in environments with a pH greater than 7. Images PMID:3125789

Ultrasonic-assisted preparation of graphene oxide carboxylic acid polyvinyl alcohol polymer film and studies of thermal stability and surface resistivity.

PubMed

Li, Yongshen; Li, Jihui; Li, Yuehai; Li, Yali; Song, Yunan; Niu, Shuai; Li, Ning

2018-01-01

In this paper, flake graphite, nitric acid and acetic anhydride are used to prepare graphene oxide carboxylic acid (GO-COOH) via an ultrasonic-assisted method, and GO-COOH and polyvinyl alcohol polymer (PVA) are used to synthesize graphene oxide carboxylic acid polyvinyl alcohol polymer (GO-COOPVA) via the ultrasonic-assisted method, and GO-COOPVA is used to manufacture graphene oxide carboxylic acid polyvinyl alcohol polymer film (GO-COOPVA film) via a solidification method, and the structure and morphology of GO-COOH, GO-COOPVA and GO-COOPVA film are characterized, and the thermal stability and surface resistivity are measured in the case of the different amount of GO-COOH. Based on the characterization and measurement, it has been successively confirmed and attested that carboxyl groups implant on 2D lattice of GO to form GO-COOH, and GO-COOH and PVA have the esterification reaction to produce GO-COOPVA, and GO-COOPVA consists of 2D lattice of GO-COOH and the chain of PVA connected in the form of carboxylic ester, and GO-COOPVA film is composed of GO-COOPVA, and the thermal stability of GO-COOPVA film obviously improves in comparison with PVA film, and the surface resistivity of GO-COOPVA film clearly decreases. Copyright © 2017 Elsevier B.V. All rights reserved.

Enhanced detection of amino acids in hydrophilic interaction chromatography electrospray tandem mass spectrometry with carboxylic acids as mobile phase additives.

PubMed

Yin, Dengyang; Hu, Xunxiu; Liu, Dantong; Du, Wencheng; Wang, Haibo; Guo, Mengzhe; Tang, Daoquan

2017-06-01

Liquid chromatography coupled with mass spectrometry technique has been widely used in the analysis of biological targets such as amino acids, peptides, and proteins. In this work, eight common single carboxylic acids or diacids, which contain different pKa have been investigated as the additives to the analysis of amino acids. As the results, carboxylic acid additive can improve the signal intensity of acidity amino acids such as Asp and Glu and the chromatographic separation of basic amino acids such as Arg, His, and Lys. In particular, the diacids have better performance than single acids. The proposed mechanism is that the diacid has hydrogen bond interaction with amino acids to reduce their polarity/amphiprotic characteristics. Besides, oxalic acid has been found having better enhancement than phthalic acid by overall consideration. Therefore, we successfully quantified the 15 amino acids in Sepia bulk pharmaceutical chemical by using oxalic acid as the additive.

Predicting the crystallization propensity of carboxylic acid buffers in frozen systems--relevance to freeze-drying.

PubMed

Sundaramurthi, Prakash; Suryanarayanan, Raj

2011-04-01

Selective crystallization of buffer components in frozen solutions is known to cause pronounced pH shifts. Our objective was to study the crystallization behavior and the consequent pH shift in frozen aqueous carboxylic acid buffers. Aqueous carboxylic acid buffers were cooled to -25°C and the pH of the solution was measured as a function of temperature. The thermal behavior of solutions during freezing and thawing was investigated by differential scanning calorimetry. The crystallized phases in frozen solution were identified by X-ray diffractometry. The malate buffer system was robust with no evidence of buffer component crystallization and hence negligible pH shift. In the citrate and tartarate systems, at initial pH

Unexpected Hydrolytic Instability of N-Acylated Amino Acid Amides and Peptides

PubMed Central

2015-01-01

Remote amide bonds in simple N-acyl amino acid amide or peptide derivatives 1 can be surprisingly unstable hydrolytically, affording, in solution, variable amounts of 3 under mild acidic conditions, such as trifluoroacetic acid/water mixtures at room temperature. This observation has important implications for the synthesis of this class of compounds, which includes N-terminal-acylated peptides. We describe the factors contributing to this instability and how to predict and control it. The instability is a function of the remote acyl group, R2CO, four bonds away from the site of hydrolysis. Electron-rich acyl R2 groups accelerate this reaction. In the case of acyl groups derived from substituted aromatic carboxylic acids, the acceleration is predictable from the substituent’s Hammett σ value. N-Acyl dipeptides are also hydrolyzed under typical cleavage conditions. This suggests that unwanted peptide truncation may occur during synthesis or prolonged standing in solution when dipeptides or longer peptides are acylated on the N-terminus with electron-rich aromatic groups. When amide hydrolysis is an undesired secondary reaction, as can be the case in the trifluoroacetic acid-catalyzed cleavage of amino acid amide or peptide derivatives 1 from solid-phase resins, conditions are provided to minimize that hydrolysis. PMID:24617596

Teratology study of amide derivatives of branched aliphatic carboxylic acids with 4-aminobenzensulfonamide in NMRI mice.

PubMed

Onishi, Yuko; Okada, Akinobu; Noyori, Hiroko; Okamura, Ai; Hen, Naama; Yagen, Boris; Bialer, Meir; Fujiwara, Michio

2013-08-01

Valproic acid (VPA), widely used to treat epilepsy, bipolar disorders, and migraine prophylaxis, is known to cause neural tube and skeletal defects in humans and animals. Aminobenzensulfonamide derivatives of VPA with branched aliphatic carboxylic acids, namely 2-methyl-N-(4-sulfamoyl-phenyl)-pentanamide (MSP), 2-ethyl-N-(4-sulfamoyl-phenyl)-butyramide (ESB), 2-ethyl-4-methyl-N-(4-sulfamoyl-phenyl)-pentanamide (EMSP), and 2-ethyl-N-(4-sulfamoyl-benzyl)-butyramide (ESBB), have shown more potent anticonvulsant activity than VPA in preclinical testing. Here, we investigated the teratogenic effects of these analogous compounds of VPA in NMRI mice. Pregnant NMRI mice were given a single subcutaneous injection of either VPA at 1.8 or 3.6 mmol/kg, or MSP, ESB, EMSP, or ESBB at 1.8, 3.6, or 4.8 mmol/kg on gestation day (GD) 8. Cesarean section was performed on GD 18, and the live fetuses were examined for external and skeletal malformations. Compared with VPA, which induced neural tube defects (NTDs) in fetuses at 1.8 and 3.6 mmol/kg, the analog derivatives induced no NTDs at dose levels up to 4.8 mmol/kg (except for a single case of exencephaly at 4.8 mmol/kg MSP). Skeletal examination showed several abnormalities mainly at the axial skeletal level with VPA at 1.8 mmol/kg. Fused vertebrae and/or fused ribs were also observed with MSP, ESB, EMSP, and ESBB, they were less severe and seen at a lower incidence that those induced by VPA at the same dose level. In addition to exerting more potent preclinical antiepileptic activity, teratology comparison indicates that aminobenzensulfonamide analogs are generally more weakly teratogenic than VPA. © 2013 Wiley Periodicals, Inc.

Design, synthesis, and biological evaluation of 2-substituted-2,3,4,9-tetrahydrospiro-β-carboline-3-carboxylic acid derivatives as first-in-class mast cell stabilizers.

PubMed

Singh, Jatinder; Shah, Ramanpreet; Singh, Dhandeep; Jaggi, Amteshwar S; Singh, Nirmal

2018-05-01

Mast cell degranulation plays a momentous role in myriad diseases like asthma, eczema, allergic rhinitis, and conjunctivitis as well as anaphylactic shock; hence, there is an unmet need for developing new mast cells stabilizers. The reported mast cell stabilizers have a heterocyclic moiety and an acidic group. Furthermore, the role of tryptophan in suppression of mast cell activation is established. Hence, we prepared constrained analogs of tryptophan, which are derivatives of 2,3,4,9-tetrahydrospiro-β-carboline-3-carboxylic acid, and evaluated them for ex vivo inhibition of compound 48/80-induced mast degranulation activity. By comparing IC 50 (μM) values with that of the standard drug sodium cromoglycate (IC 50  = 0.489 ± 0.003 μM), compounds with bulky groups like heptyl (compound 9; IC 50  = 0.389 ± 0.015 μM) and octyl (compound 10; IC 50  = 0.354 ± 0.023 μM) were found to be of similar potency as sodium cromoglycate. Furthermore, the polar group-containing compounds like the chloropropyl (compound 16; IC 50  = 0.382 ± 0.083 μM) and benzoyl derivative (compound 14; IC 50  = 00.469 ± 0.032 μM) were also found to be of similar potency as sodium cromoglycate. This is a seminal study of spiro-β-carboline mast cell stabilization having a wider scope in mast cell research; yet, the mechanism of action remains elusive. © 2018 Deutsche Pharmazeutische Gesellschaft.

Molecular complexes of alprazolam with carboxylic acids, boric acid, boronic acids, and phenols. Evaluation of supramolecular heterosynthons mediated by a triazole ring.

PubMed

Varughese, Sunil; Azim, Yasser; Desiraju, Gautam R

2010-09-01

A series of molecular complexes, both co-crystals and salts, of a triazole drug-alprazolam-with carboxylic acids, boric acid, boronic acids, and phenols have been analyzed with respect to heterosynthons present in the crystal structures. In all cases, the triazole ring behaves as an efficient hydrogen bond acceptor with the acidic coformers. The hydrogen bond patterns exhibited with aromatic carboxylic acids were found to depend on the nature and position of the substituents. Being a strong acid, 2,6-dihydroxybenzoic acid forms a salt with alprazolam. With aliphatic dicarboxylic acids alprazolam forms hydrates and the water molecules play a central role in synthon formation and crystal packing. The triazole ring makes two distinct heterosynthons in the molecular complex with boric acid. Boronic acids and phenols form consistent hydrogen bond patterns, and these are seemingly independent of the substitutional effects. Boronic acids form noncentrosymmetric cyclic synthons, while phenols form O--H...N hydrogen bonds with the triazole ring.

Mechanism of formation of humus coatings on mineral surfaces 1. Evidence for multidentate binding of organic acids from compost leachate on alumina

USGS Publications Warehouse

Wershaw, R. L.; Leenheer, J.A.; Sperline, R.P.; Song, Yuan; Noll, L.A.; Melvin, R.L.; Rigatti, G.P.

1995-01-01

Measurements of the infrared linear dichroism of carboxylate groups of organic acids from compost leachate adsorbed to an alumina surface and the enthalpy of adsorption of this reaction have been made. The linear dichroism measurements indicated that the carboxylate groups are not free to rotate. This limited rotation probably results from bidentate binding of the carboxylate groups. The molar enthalpy of adsorption of the acids is approximately −100 kJ mol−1. This high value for enthalpy of adsorption may best be explained by assuming that two or more carboxylate groups on a single dissolved organic carbon (DOC) molecule coordinate to the surficial aluminium ions.

Organocatalyzed, Visible-Light Photoredox-Mediated, One-Pot Minisci Reaction Using Carboxylic Acids via N-(Acyloxy)phthalimides.

PubMed

Sherwood, Trevor C; Li, Ning; Yazdani, Aliza N; Dhar, T G Murali

2018-03-02

An improved, one-pot Minisci reaction has been developed using visible light, an organic photocatalyst, and carboxylic acids as radical precursors via the intermediacy of in situ-generated N-(acyloxy)phthalimides. The conditions employed are mild, demonstrate a high degree of functional group tolerance, and do not require a large excess of the carboxylic acid reactant. As a result, this reaction can be applied to drug-like scaffolds and molecules with sensitive functional groups, enabling late-stage functionalization, which is of high interest to medicinal chemistry.

Separation of aromatic carboxylic acids using quaternary ammonium salts on reversed-phase HPLC. 2. Application for the analysis of Loy Yang coal oxidation products

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kawamura, K.; Okuwaki, A.; Verheyen, T.V.

In order to develop separation processes and analytical methods for aromatic carboxylic acids for the coal oxidation products, the separation behavior of aromatic carboxylic acids on a reversed-phase HPLC using eluent containing quaternary ammonium salt was optimized using the solvent gradient method. This method was applied for the analysis of Loy Yang coal oxidation products. It was confirmed that the analytical data using this method were consistent with those determined using gas chromatography.

Commandant’s International Technical Series. Volume 9. International Regulations on the Prevention of Pollution from Ships Carrying Hazardous Chemicals in Bulk.

DTIC Science & Technology

1985-12-01

Styrene monomer 2055 B Sulphuric acid 1830 C " Sulphuric acid, spent 1832 C - Sulphurous acid 1633 (C) Sunflover oil D...anhydrides (e.g. formic, acetic); .3 halogenated carboxylic acids (e.g. chloracetic); .4 sulpnonic acids (e.g. benzene sulphonic); .5 caustic alkalis...acetic); (iii) halogenated carboxylic acids (e.g. cbloracetic); (iv) sulphonic acids (e.g. benzene sulphonic);II (v) caustic alkalis (e.g. sodium

Method for the production of dicarboxylic acids

DOEpatents

Nghiem, N.P.; Donnelly, M.; Millard, C.S.; Stols, L.

1999-02-09

The present invention is an economical fermentation method for the production of carboxylic acids comprising the steps of (a) inoculating a medium having a carbon source with a carboxylic acid-producing organism; (b) incubating the carboxylic acid-producing organism in an aerobic atmosphere to promote rapid growth of the organism thereby increasing the biomass of the organism; (c) controllably releasing oxygen to maintain the aerobic atmosphere; (d) controllably feeding the organism having increased biomass with a solution containing the carbon source to maintain the concentration of the carbon source within the medium of about 0.5 g/l up to about 1 g/l; (e) depriving the aerobic atmosphere of oxygen to produce an anaerobic atmosphere to cause the organism to undergo anaerobic metabolism; (f) controllably feeding the organism having increased biomass a solution containing the carbon source to maintain the concentration of the carbon source within the medium of {>=}1 g/l; and (g) converting the carbon source to carboxylic acids using the anaerobic metabolism of the organism. 7 figs.

Discovery of a Novel Series of CRTH2 (DP2) Receptor Antagonists Devoid of Carboxylic Acids

PubMed Central

2011-01-01

Antagonism of the CRTH2 receptor represents a very attractive target for a variety of allergic diseases. Most CRTH2 antagonists known to date possess a carboxylic acid moiety, which is essential for binding. However, potential acid metabolites O-acyl glucuronides might be linked to idiosynchratic toxicity in humans. In this communication, we describe a new series of compounds that lack the carboxylic acid moiety. Compounds with high affinity (Ki < 10 nM) for the receptor have been identified. Subsequent optimization succeeded in reducing the high metabolic clearance of the first compounds in human and rat liver microsomes. At the same time, inhibition of the CYP isoforms was optimized, giving rise to stable compounds with an acceptable CYP inhibition profile (IC50 CYP2C9 and 2C19 > 1 μM). Taken together, these data show that compounds devoid of carboxylic acid groups could represent an interesting alternative to current CRTH2 antagonists in development. PMID:24900284

Method for the production of dicarboxylic acids

DOEpatents

Nghiem, Nhuan Phu; Donnelly, Mark; Millard, Cynthia S.; Stols, Lucy

1999-01-01

The present invention is an economical fermentation method for the production of carboxylic acids comprising the steps of a) inoculating a medium having a carbon source with a carboxylic acid-producing organism; b) incubating the carboxylic acid-producing organism in an aerobic atmosphere to promote rapid growth of the organism thereby increasing the biomass of the organism; c) controllably releasing oxygen to maintain the aerobic atmosphere; d) controllably feeding the organism having increased biomass with a solution containing the carbon source to maintain the concentration of the carbon source within the medium of about 0.5 g/L up to about 1 g/L; e) depriving the aerobic atmosphere of oxygen to produce an anaerobic atmosphere to cause the organism to undergo anaerobic metabolism; f) controllably feeding the organism having increased biomass a solution containing the carbon source to maintain the concentration of the carbon source within the medium of .gtoreq.1 g/L; and g) converting the carbon source to carboxylic acids using the anaerobic metabolism of the organism.

Seven organic salts assembled from hydrogen-bonds of N-H⋯O, O-H⋯O, and C-H⋯O between acidic compounds and bis(benzimidazole)

NASA Astrophysics Data System (ADS)

Jin, Shouwen; Liu, Hui; Gao, Xin Jun; Lin, Zhanghui; Chen, Guqing; Wang, Daqi

2014-10-01

Seven crystalline organic acid-base adducts derived from 1,4-bis(benzimidazol-2-yl)butane/1,2-bis(2-benzimidazolyl)-1,2-ethanediol and acidic components (picric acid, 2-hydroxy-5-(phenyldiazenyl)benzoic acid, 5-sulfosalicylic acid, oxalic acid, and 1,5-naphthalenedisulfonic acid) were prepared and characterized by the single crystal X-ray diffraction analysis, IR, mp, and elemental analysis. All of the seven compounds are organic salts involving proton transfer from the acidic components to the bis(benzimidazole). For the salt 3, although a competing carboxyl group is present, it has been observed that only the proton at the -SO3H group is deprotonized rather than the H at the COOH. While in the salt 7, both COOH and SO3H were ionized to exhibit a valence number of -2. For 4, the oxalic acid existed as unionized molecule, monoanion, and dianion simultaneously in one compound. All supramolecular architectures of the organic salts 1-7 involve extensive intermolecular N-H⋯O, O-H⋯O, and C-H⋯O hydrogen bonds as well as other noncovalent interactions. Since the potentially hydrogen bonding phenol group is present in the ortho position to the carboxyl group in 2, 3, and 7, it forms the more facile intramolecular O-H⋯O hydrogen bonding. The role of weak and strong noncovalent interactions in the crystal packing is ascertained. These weak interactions combined, all the complexes displayed 3D framework structure.

Stereospecific synthesis of syn-α-oximinoamides by a three-component reaction of isocyanides, syn-chlorooximes, and carboxylic acids.

PubMed

Pirali, Tracey; Mossetti, Riccardo; Galli, Simona; Tron, Gian Cesare

2011-07-15

A stereospecific multicomponent reaction among isocyanides, syn-chlorooximes, and carboxylic acids provides an efficient synthesis of biologically relevant syn-α-oximinoamides. © 2011 American Chemical Society

High-Throughput Analysis of Methylmalonic Acid in Serum, Plasma, and Urine by LC-MS/MS. Method for Analyzing Isomers Without Chromatographic Separation.

PubMed

Kushnir, Mark M; Nelson, Gordon J; Frank, Elizabeth L; Rockwood, Alan L

2016-01-01

Measurement of methylmalonic acid (MMA) plays an important role in the diagnosis of vitamin B12 deficiency. Vitamin B12 is an essential cofactor for the enzymatic carbon rearrangement of methylmalonyl-CoA (MMA-CoA) to succinyl-CoA (SA-CoA), and the lack of vitamin B12 leads to elevated concentrations of MMA. Presence of succinic acid (SA) complicates the analysis because mass spectra of MMA and SA are indistinguishable, when analyzed in negative ion mode and the peaks are difficult to resolve chromatographically. We developed a method for the selective analysis of MMA that exploits the significant difference in fragmentation patterns of di-butyl derivatives of the isomers MMA and SA in a tandem mass spectrometer when analyzed in positive ion mode. Tandem mass spectra of di-butyl derivatives of MMA and SA are very distinct; this allows selective analysis of MMA in the presence of SA. The instrumental analysis is performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in positive ion mode, which is, in combination with selective extraction of acidic compounds, is highly selective for organic acids with multiple carboxyl groups (dicarboxylic, tricarboxylic, etc.). In this method organic acids with a single carboxyl group are virtually undetectable in the mass spectrometer; the only organic acid, other than MMA, that is detected by this method is its isomer, SA. Quantitative measurement of MMA in this method is performed using a deconvolution algorithm, which mathematically resolves the signal corresponding to MMA and does not require chromatographic resolution of the MMA and SA peaks. Because of its high selectivity, the method utilizes isocratic chromatographic separation; reconditioning and re-equilibration of the chromatographic column between injections is unnecessary. The above features of the method allow high-throughput analysis of MMA with analysis cycle time of 1 min.

Photoelectron spectra of some antibiotic building blocks: 2-azetidinone and thiazolidine-carboxylic acid.

PubMed

Ahmed, Marawan; Ganesan, Aravindhan; Wang, Feng; Feyer, Vitaliy; Plekan, Oksana; Prince, Kevin C

2012-08-23

X-ray photoelectron spectra of the core and valence levels of the fundamental building blocks of β-lactam antibiotics have been investigated and compared with theoretical calculations. The spectra of the compounds 2-azetidinone and the 2- and 4-isomers of thiazolidine-carboxylic acid are interpreted in the light of theoretical calculations. The spectra of the two isomers of thiazolidine-carboxylic acid are rather similar, as expected, but show clear effects due to isomerization. Both isomers are analogues of proline, which is well-known to populate several low energy conformers in the gas phase. We have investigated the low energy conformers of thiazolidine-4-carboxylic acid theoretically in more detail and find some spectroscopic evidence that multiple conformers may be present. The measured valence levels are assigned for all three compounds, and the character of the frontier orbitals is identified and analyzed.

Ink composition for making a conductive silver structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walker, Steven B.; Lewis, Jennifer A.

An ink composition for making a conductive silver structure comprises a silver salt and a complex of (a) a complexing agent and a short chain carboxylic acid or (b) a complexing agent and a salt of a short chain carboxylic acid, according to one embodiment. A method for making a silver structure entails combining a silver salt and a complexing agent, and then adding a short chain carboxylic acid or a salt of the short chain carboxylic acid to the combined silver salt and a complexing agent to form an ink composition. A concentration of the complexing agent in themore » ink composition is reduced to form a concentrated formulation, and the silver salt is reduced to form a conductive silver structure, where the concentrated formulation and the conductive silver structure are formed at a temperature of about 120.degree. C. or less.« less

Studies of the chemical basis of the origin of protein synthesis Initiation and direction of peptide growth

NASA Technical Reports Server (NTRS)

Mullins, D. W., Jr.; Lacey, J. C., Jr.

1980-01-01

The data presented in this paper show that the ease of nonenzymatic activation of carboxylic acids by ATP at pH 5 varies directly with the pKa of the carboxyl group, and is consistent with the idea that it is the protonated form of the carboxyl group which participates in the activation reaction. Consequently, since most N-blocked amino acids have higher pKas than do their unblocked forms, they are activated more readily, and it has been demonstrated that this principle applies to peptides as well, which are activated more rapidly than single amino acids. It is proposed that this fact may be partly responsible for the origin of two important features still observed in contemporary protein synthesis: (1) initiation in prokaryotes is accomplished with an N-blocked amino acid, and (2) elongation in all living systems occurs at the carboxyl end of the growing peptide.

Ball Milling Assisted Solvent and Catalyst Free Synthesis of Benzimidazoles and Their Derivatives.

PubMed

El-Sayed, Taghreed H; Aboelnaga, Asmaa; Hagar, Mohamed

2016-08-24

Benzoic acid and o-phenylenediamine efficiently reacted under the green solvent-free Ball Milling method. Several reaction parameters were investigated such as rotation frequency; milling balls weight and milling time. The optimum reaction condition was milling with 56.6 g weight of balls at 20 Hz frequency for one hour milling time. The study was extended for synthesis of a series of benzimidazol-2-one or benzimidazol-2-thione using different aldehydes; carboxylic acids; urea; thiourea or ammonium thiocyanate with o-phenylenediamine. Moreover; the alkylation of benzimidazolone or benzimidazolthione using ethyl chloroacetate was also studied.

Preparation of 2-hydroxy-5-oxoproline and analogs thereof

DOEpatents

Martinez, Rodolfo A.; Unkefer, Pat J.

2001-01-01

The compound 2-hydroxy-5-oxoproline and analogs thereof may be used to produce an increase in carbon dioxide fixation, growth, dry weight, nutritional value (proteins and amino acids), nodulation and nitrogen fixation and photosynthetically derived chemical energy when applied to plants through their roots and/or through their foliar portions. The present invention includes an essentially quantitative chemical synthesis for this compound which is performed in a single step reaction of Fremy's Salt (potassium nitrosodisulphonate) with either glutamine or 2-pyrrolidone-5-carboxylic acid. Fremy's salt (potassium nitrosodisulphonate) is available commercially, or can be readily synthesized.

Synthesis of 1-indanones with a broad range of biological activity

PubMed Central

Turek, Marika; Szczęsna, Dorota; Koprowski, Marek

2017-01-01

This comprehensive review describes methods for the preparation of 1-indanones published in original and patent literature from 1926 to 2017. More than 100 synthetic methods utilizing carboxylic acids, esters, diesters, acid chlorides, ketones, alkynes, alcohols etc. as starting materials, have been performed. This review also covers the most important studies on the biological activity of 1-indanones and their derivatives which are potent antiviral, anti-inflammatory, analgesic, antimalarial, antibacterial and anticancer compounds. Moreover, they can be used in the treatment of neurodegenerative diseases and as effective insecticides, fungicides and herbicides. PMID:28382183

An electrochemical study of natural and chemically controlled eumelanin

NASA Astrophysics Data System (ADS)

Xu, Ri; Prontera, Carmela Tania; Di Mauro, Eduardo; Pezzella, Alessandro; Soavi, Francesca; Santato, Clara

2017-12-01

Eumelanin is the most common form of the pigment melanin in the human body, with functions including antioxidant behavior, metal chelation, and free radical scavenging. This biopigment is of interest for biologically derived batteries and supercapacitors. In this work, we characterized the voltammetric properties of chemically controlled eumelanins produced from 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA) building blocks, namely, DHI-melanin, DHICA-melanin, and natural eumelanin, extracted from the ink sac of cuttlefish, Sepia melanin. Eumelanin electrodes were studied for their cyclic voltammetric properties in acidic buffers including Na+, K+, NH4+, and Cu2+ ions.

Formation of biologically relevant carboxylic acids during the gamma irradiation of acetic acid

NASA Technical Reports Server (NTRS)

Negron-Mendoza, A.; Ponnamperuma, C.

1976-01-01

Irradiation of aqueous solutions of acetic acid with gamma rays produced several carboxylic acids in small yield. Their identification was based on the technique of gas chromatography combined with mass spectrometry. Some of these acids are Krebs Cycle intermediates. Their simultaneous formation in experiments simulating the primitive conditions on the earth suggests that metabolic pathways may have had their origin in prebiotic chemical processes.

Infrared spectroscopic studies of the effect of elevated temperature on the association of pyroglutamic acid with clay and other minerals

NASA Astrophysics Data System (ADS)

Macklin, John W.; White, David H.

Fourier transform i.r. measurements of L-pyroglutamic acid dispersed in a matrix of a clay, silica or alumina have been obtained at various temperatures between 25 and 220°C. The i.r. spectrum of L-pyroglutamic acid varies in a manner slightly dependent upon the matrix material and shows considerable change as the temperature of the mixtures is increased. The differences in the spectrum at elevated temperatures are explained in terms of a chemical reaction between hydroxyl groups in the matrix and the carboxylic acid. The i.r. spectra of trimethylsilyl derivatives of L-pyroglutamic acid and aluminum pyroglutamate were also measured to assist the understanding of spectra and interpretation of the spectral changes dependent upon increasing temperature.

Infrared spectroscopic studies of the effect of elevated temperature on the association of pyroglutamic acid with clay and other minerals

NASA Technical Reports Server (NTRS)

Macklin, J. W.; White, D. H.

1985-01-01

Fourier transform i.r. measurements of L-pyroglutamic acid dispersed in a matrix of a clay, silica or alumina have been obtained at various temperatures between 25 and 220 degrees C. The i.r. spectrum of L-pyroglutamic acid varies in a manner dependent upon the matrix material and shows considerable change as the temperature of the mixtures is increased. The differences in the spectrum at elevated temperatures are explained in terms of a chemical reaction between hydroxyl groups in the matrix and the carboxylic acid. The i.r. spectra of trimethylsilyl derivatives of L-pyroglutamic acid and aluminum pyroglutamate were also measured to assist the understanding of spectra and interpretation of the spectral changes dependent upon increasing temperature.

Nanoporous carbon materials with enhanced supercapacitance performance and non-aromatic chemical sensing with C1/C2 alcohol discrimination

NASA Astrophysics Data System (ADS)

Shrestha, Lok Kumar; Adhikari, Laxmi; Shrestha, Rekha Goswami; Adhikari, Mandira Pradhananga; Adhikari, Rina; Hill, Jonathan P.; Pradhananga, Raja Ram; Ariga, Katsuhiko

2016-01-01

We have investigated the textural properties, electrochemical supercapacitances and vapor sensing performances of bamboo-derived nanoporous carbon materials (NCM). Bamboo, an abundant natural biomaterial, was chemically activated with phosphoric acid at 400 °C and the effect of impregnation ratio of phosphoric acid on the textural properties and electrochemical performances was systematically investigated. Fourier transform-infrared (FTIR) spectroscopy confirmed the presence of various oxygen-containing surface functional groups (i.e. carboxyl, carboxylate, carbonyl and phenolic groups) in NCM. The prepared NCM are amorphous in nature and contain hierarchical micropores and mesopores. Surface areas and pore volumes were found in the range 218-1431 m2 g-1 and 0.26-1.26 cm3 g-1, respectively, and could be controlled by adjusting the impregnation ratio of phosphoric acid and bamboo cane powder. NCM exhibited electrical double-layer supercapacitor behavior giving a high specific capacitance of c.256 F g-1 at a scan rate of 5 mV s-1 together with high cyclic stability with capacitance retention of about 92.6% after 1000 cycles. Furthermore, NCM exhibited excellent vapor sensing performance with high sensitivity for non-aromatic chemicals such as acetic acid. The system would be useful to discriminate C1 and C2 alcohol (methanol and ethanol).

ON THE FORMATION OF BENZOIC ACID AND HIGHER-ORDER BENZENE CARBOXYLIC ACIDS IN INTERSTELLAR MODEL ICE GRAINS

DOE Office of Scientific and Technical Information (OSTI.GOV)

McMurtry, Brandon M.; Saito, Sean E. J.; Turner, A

With a binary ice mixture of benzene (C{sub 6}H{sub 6}) and carbon dioxide (CO{sub 2}) at 10 K under contamination-free ultrahigh vacuum conditions, the formation of benzene carboxylic acids in interstellar ice grains was studied. Fourier transform infrared spectroscopy was used to probe for the formation of new species during the chemical processing of the ice mixture and during the following temperature-programmed desorption. Newly formed benzene carboxylic acid species, i.e., benzoic acid, as well as meta - and para -benzene dicarboxylic acid, were assigned using newly emerging bands in the infrared spectrum; a reaction mechanism, along with rate constants, wasmore » proposed utilizing the kinetic fitting of the coupled differential equations.« less

Antifungal sourdough lactic acid bacteria as biopreservation tool in quinoa and rice bread.

PubMed

Axel, Claudia; Brosnan, Brid; Zannini, Emanuele; Furey, Ambrose; Coffey, Aidan; Arendt, Elke K

2016-12-19

The use of sourdough fermented with specific strains of antifungal lactic acid bacteria can reduce chemical preservatives in bakery products. The main objective of this study was to investigate the production of antifungal carboxylic acids after sourdough fermentation of quinoa and rice flour using the antifungal strains Lactobacillus reuteri R29 and Lactobacillus brevis R2Δ as bioprotective cultures and the non-antifungal L. brevis L1105 as a negative control strain. The impact of the fermentation substrate was evaluated in terms of metabolic activity, acidification pattern and quantity of antifungal carboxylic acids. These in situ produced compounds (n=20) were extracted from the sourdough using a QuEChERS method and detected by a new UHPLC-MS/MS chromatography. Furthermore, the sourdough was applied in situ using durability tests against environmental moulds to investigate the biopreservative potential to prolong the shelf life of bread. Organic acid production and TTA values were lowest in rice sourdough. The sourdough fermentation of the different flour substrates generated a complex and significantly different profile of carboxylic acids. Extracted quinoa sourdough detected the greatest number of carboxylic acids (n=11) at a much higher concentration than what was detected from rice sourdough (n=9). Comparing the lactic acid bacteria strains, L. reuteri R29 fermented sourdoughs contained generally higher concentrations of acetic and lactic acid but also the carboxylic acids. Among them, 3-phenyllactic acid and 2-hydroxyisocaproic acid were present at a significant concentration. This was correlated with the superior protein content of quinoa flour and its high protease activity. With the addition of L. reuteri R29 inoculated sourdough, the shelf life was extended by 2 days for quinoa (+100%) and rice bread (+67%) when compared to the non-acidified controls. The L. brevis R2Δ fermented sourdough bread reached a shelf life of 4 days for quinoa (+100%) and rice (+33%). However, the shelf life was similar to the chemically acidified control indicating that the preservation effect of the carboxylic acids seems to have a minor contribution effect on the antifungal activity in gluten-free breads. Copyright © 2016 Elsevier B.V. All rights reserved.

Chemiluminescence of Secondary Peroxyesters.

DTIC Science & Technology

1980-11-14

phenylethylperoxybenzoates was investiqlated. Thermolysis in benzene gives acetophenone and the corresponding carboxYlic acid . The study of the reactiol...these compounds undergo unimolecular thermolysis to qenerate the appropriate carboxylic acid add carbonyl compound; eq. 2. We estimated, using...prepared by reaction of 1 -phenylethyl hydroperoxide with the appropriate activated acid precursor. We prepared the hydroperoxide by two different routes

Dissolving Carboxylic Acids and Primary Amines on the Overhead Projector

ERIC Educational Resources Information Center

Solomon, Sally D.; Rutkowsky, Susan A.

2010-01-01

Liquid carboxylic acids (or primary amines) with limited solubility in water are dissolved by addition of aqueous sodium hydroxide (or hydrochloric acid) on the stage of an overhead projector using simple glassware and very small quantities of chemicals. This effective and colorful demonstration can be used to accompany discussions of the…

Structural environments of carboxyl groups in natural organic molecules from terrestrial systems. Part 1: Infrared spectroscopy

NASA Astrophysics Data System (ADS)

Hay, Michael B.; Myneni, Satish C. B.

2007-07-01

Carboxyls play an important role in the chemistry of natural organic molecules (NOM) in the environment, and their behavior is dependent on local structural environment within the macromolecule. We studied the structural environments of carboxyl groups in dissolved NOM from the Pine Barrens (New Jersey, USA), and IHSS NOM isolates from soils and river waters using attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy. It is well established that the energies of the asymmetric stretching vibrations of the carboxylate anion (COO -) are sensitive to the structural environment of the carboxyl group. These energies were compiled from previous infrared studies on small organic acids for a wide variety of carboxyl structural environments and compared with the carboxyl spectral features of the NOM samples. We found that the asymmetric stretching peaks for all NOM samples occur within a narrow range centered at 1578 cm -1, suggesting that all NOM samples examined primarily contain very similar carboxyl structures, independent of sample source and isolation techniques employed. The small aliphatic acids containing hydroxyl (e.g., D-lactate, gluconate), ether/ester (methoxyacetate, acetoxyacetate), and carboxylate (malonate) substitutions on the α-carbon, and the aromatic acids salicylate ( ortho-OH) and furancarboxylate ( O-heterocycle), exhibit strong overlap with the NOM range, indicating that similar structures may be common in NOM. The width of the asymmetric peak suggests that the structural heterogeneity among the predominant carboxyl configurations in NOM is small. Changes in peak area with pH at energies distant from the peak at 1578 cm -1, however, may be indicative of a small fraction of other aromatic carboxyls and aliphatic structures lacking α-substitution. This information is important in understanding NOM-metal and mineral-surface complexation, and in building appropriate structural and mechanistic models of humic materials.

Use of RSM for the multivariate, simultaneous multiobjective optimization of the operating conditions of aliphatic carboxylic acids ion-exclusion chromatography column: Quantitative study of hydrodynamic, isotherm, and thermodynamic behavior.

PubMed

Shojaeimehr, Tahereh; Rahimpour, Farshad; Schwarze, Michael; Repke, Jens-Uwe; Godini, Hamid Reza; Wozny, Günter

2018-04-15

The present study evaluates the capability of ion exclusion chromatography (IEC) of short chain aliphatic carboxylic acids using a cation exchange column (8% sulfonated cross-linked styrene-divinylbenzene copolymer) in different experimental conditions. Since one of the prerequisites to the development of an efficient carboxylic acid separation process is to obtain the optimum operational conditions, response surface methodology (RSM) was used to develop an approach to evaluate carboxylic acids separation process in IEC columns. The effect of the operating conditions such as column temperature, sulfuric acid concentration as the mobile phase, and the flow rate was studied using Central Composite Face (CCF) design. The optimum operating conditions for the separate injection of lactic acid and acetic acid is temperature of 75 °C, sulfuric acid concentration of 0.003 N for both acids and flow rate of 0.916 (0.886) mL/min for acetic acid (lactic acid). Likewise, the optimum conditions for the simultaneous injection of acetic and lactic acid mixture are the column temperature of 68 °C, sulfuric acid concentration of 0.0003 N, and flow rate of 0.777 mL/min. In the next step, the adsorption equilibria of acetic acid and lactic acid on the stationary phase were investigated through a series of Frontal Analysis (FA), Frontal Analysis by Characteristic Points (FACP), and using Langmuir isotherm model. The results showed an excellent agreement between the model and experimental data. Finally, the results of thermodynamic studies proved that the IEC process for separation of acetic and lactic acid is a spontaneous, feasible, exothermic, and random process with a physical adsorption mechanism. The results of the current paper can be a valuable information in the stages of designing IEC columns for separation of aliphatic carboxylic acids. Copyright © 2018 Elsevier B.V. All rights reserved.

Chloride channel blockers activate an endogenous cationic current in oocytes of Bufo arenarum.

PubMed

Cavarra, M S; del Mónaco, S M; Kotsias, B A

2004-07-01

A two-electrode, voltage-clamp technique was used to measure the effect of the Cl(-) channel blockers, 9-anthracene carboxylic acid and niflumic acid, upon the ionic currents of oocytes of the South American toad Bufo arenarum. The main results were: (1) both blockers produced a reversible increase of the outward currents on a dose-dependent manner; (2) the activated outward current was voltage dependent; (3) the 9-anthracene carboxylic acid-sensitive current was blocked with barium; and (4) the effect of 9-anthracene carboxylic acid was more pronounced in a zero-K(+) solution than in standard (2 mmol l(-1)) or high (20 mmol l(-1)) K(+) solutions, indicating that a K(+) conductance is activated. The effect of the Cl(-) channel blockers could be due to a direct interaction with endogenous cationic channels. Another possible explanation is that Cl(-) that enter the cell during depolarizing steps in control solution inhibit this cationic conductance; thus, the blockade of Cl(-) channels by 9-anthracene carboxylic acid and niflumic acid would remove this inhibition, allowing the cationic current to flow freely.

Preferential deprotonation and conformational stability of dicarboxylic acids: A packing effect

NASA Astrophysics Data System (ADS)

Barooah, Nilotpal; Singh, W. Marjit; Baruah, Jubaraj B.

2008-03-01

Crystal structures of a series of salts of (6-carboxymethyl-1,3,5,7-tetraoxo-3,5,6,7-tetrahydro-1 H-pyrrolo[3,4- f]isoindol-2-yl)-acetic acid ( 1) and 2-carboxymethyl-1,3-dioxo-2,3-dihydro-1 H-isoinodole-5-carboxylic acid ( 2) with different polynuclear nitrogen containing heterocyclic compounds, namely, quinoline, 1,10-phenanthroline and 8-hydroxyquinoline are determined. In the case of salt of 1 with quinolinium and 1,10-phenanthrolinium cations syn disposition between the carboxylate anion and carboxylic acid groups is observed; whereas in the case of the 8-hydroxyquinolinium salt of 1, it is the anti disposition. It is also found that the solid state structure of 1,10-phenanthrolinium salt of 2 has deprotonation at the aromatic end, whereas in 8-hydroxy-quinolinium salt of 2 is formed by deprotonation of carboxylic acid group on the aliphatic side. The dicarboxylic acid 2 forms 1:2 co-crystals with quinoline. From crystallographic study it is shown that the weak interactions become prominent in stabilising the observed conformers and also in stabilising specific deprotonated species.

On the formation of niacin (vitamin B3) and pyridine carboxylic acids in interstellar model ices

NASA Astrophysics Data System (ADS)

McMurtry, Brandon M.; Turner, Andrew M.; Saito, Sean E. J.; Kaiser, Ralf I.

2016-06-01

The formation of pyridine carboxylic acids in interstellar ice grains was simulated by electron exposures of binary pyridine (C5H5N)-carbon dioxide (CO2) ice mixtures at 10 K under contamination-free ultrahigh vacuum conditions. Chemical processing of the pristine ice and subsequent warm-up phase was monitored on line and in situ via Fourier transform infrared spectroscopy to probe for the formation of new radiation induced species. In the infrared spectra of the irradiated ice, bands assigned to nicotinic acid (niacin; vitamin B3; m-C5H4NCOOH) along with 2,3-, 2,5-, 3,4-, and 3,5-pyridine dicarboxylic acid (C5H3N(COOH)2) were unambiguously identified along with the hydroxycarbonyl (HOCO) radical. Our study suggests that the reactive pathway responsible for pyridine carboxylic acids formation involves a HOCO intermediate, which forms through the reaction of suprathermal hydrogen ejected from pyridine with carbon dioxide. The newly formed pyridinyl radical may then undergo radical-radical recombination with a hydroxycarbonyl radical to form a pyridine carboxylic acid.

Field Observation of Heterogeneous Formation of Dicarboxylic acids, Keto-carboxylic acids, α-Dicarbonyls and Nitrate in Xi'an, China during Asian dust storm periods

NASA Astrophysics Data System (ADS)

Wang, G.; Wang, J.; Ren, Y.; Li, J.

2015-12-01

To understand the formation mechanism of secondary organic aerosols (SOA) on dust surfaces, this study investigated the concentrations and compositions of dicarboxylic acids (C2-C11), keto-carboxylic acids (C3-C7), α-dicarbonyls and inorganic ions in size-segregated aerosols (9-stages) collected in Xi'an, China during the nondust storm and dust storm periods of 2009 and 2011. During the events the ambient particulate dicarboxylic acids were 932-2240 ng m-3, which are comparable and even higher than those in nondust periods. Molecular compositions of the above SOA are similar to those in nondust periods with oxalic acid being the leading species. In the presence of the dust storms, all the above mentioned SOA species in Xi'an were predominantly enriched on the coarse particles (>2.1μm), and oxalic acid well correlated with NO3- (R2=0.72, p<0.001) rather than SO42-.This phenomenon differs greatly from the SOA in any other nondust period that is characterized by an enrichment of oxalic acid in fine particles and a strong correlation of oxalic acid with SO42-. Our results further demonstrate that NO3- in the dust periods in Xi'an was mostly derived from secondary oxidation, whereas SO42- during the events was largely derived from surface soil of Gobi deserts. We propose a formation pathway to explain these observations, in which nitric acid and/or nitrogen oxides react with dust to produce Ca(NO3)2 and form a liquid phase on the surface of dust aerosols via water vapor-absorption of Ca(NO3)2, followed by a partitioning of the gas-phase water-soluble organic precursors (e.g.,glyoxal and methylglyoxal) into the aqueous-phase and a subsequent oxidation into oxalic acid. To the best of our knowledge, we found for the first time the enrichment of glyoxal and methylglyoxal on dust surface. Our data suggest an important role of nitrate in the heterogeneous formation process of SOA on the surface of Asian dust.

Approaches to α-amino acids via rearrangement to electron-deficient nitrogen: Beckmann and Hofmann rearrangements of appropriate carboxyl-protected substrates

PubMed Central

Rao, V Mohana

2012-01-01

Summary The titled approaches were effected with various 2-substituted benzoylacetic acid oximes 3 (Beckmann) and 2-substituted malonamic acids 9 (Hofmann), their carboxyl groups being masked as a 2,4,10-trioxaadamantane unit (an orthoacetate). The oxime mesylates have been rearranged with basic Al2O3 in refluxing CHCl3, and the malonamic acids with phenyliodoso acetate and KOH/MeOH. Both routes are characterized by excellent overall yields. Structure confirmation of final products was conducted with X-ray diffraction in selected cases. The final N-benzoyl and N-(methoxycarbonyl) products are α-amino acids with both carboxyl and amino protection; hence, they are of great interest in peptide synthesis. PMID:23019476

Design, synthesis and biological evaluation of 7-nitro-1H-indole-2-carboxylic acid derivatives as allosteric inhibitors of fructose-1,6-bisphosphatase.

PubMed

Bie, Jianbo; Liu, Shuainan; Zhou, Jie; Xu, Bailing; Shen, Zhufang

2014-03-15

A series of novel indole derivatives was synthesized as inhibitors of fructose-1,6-bisphosphatase (FBPase). Extensive structure-activity relationships were conducted and led to a potent FBPase inhibitor 3.9 with an IC₅₀ of 0.99 μM. The binding mode of this series of indoles was predicted using CDOCKER algorithm. The results of this research will shed light on the further design and optimization of novel small molecules as FBPase inhibitors. Copyright © 2014 Elsevier Ltd. All rights reserved.

Ambient Temperature Synthesis of High Enantiopurity N-Protected Peptidyl Ketones by Peptidyl Thiol Ester–Boronic Acid Cross-Coupling

PubMed Central

Yang, Hao; Li, Hao; Wittenberg, Rüdiger; Egi, Masahiro; Huang, Wenwei; Liebeskind, Lanny S.

2009-01-01

α-Amino acid thiol esters derived from N-protected mono-, di-, and tripeptides couple with aryl, π-electron-rich heteroaryl, or alkenyl boronic acids in the presence of stoichiometric Cu(I) thiophene-2-carboxylate (CuTC) and catalytic Pd2(dba)3/triethylphosphite to generate the corresponding N-protected peptidyl ketones in good to excellent yields and in high enantiopurity. Triethylphosphite plays a key role as a supporting ligand by mitigating an undesired palladium-catalyzed decarbonylation-β-elimination of the α-amino thiol esters. The peptidyl ketone synthesis proceeds at room temperature under non-basic conditions and demonstrates a high tolerance to functionality. PMID:17263394

Accumulation and Transport of 1-Aminocyclopropane-1-Carboxylic Acid (ACC) in Plants: Current Status, Considerations for Future Research and Agronomic Applications

PubMed Central

Vanderstraeten, Lisa; Van Der Straeten, Dominique

2017-01-01

1-aminocyclopropane-1-carboxylic acid (ACC) is a non-protein amino acid acting as the direct precursor of ethylene, a plant hormone regulating a wide variety of vegetative and developmental processes. ACC is the central molecule of ethylene biosynthesis. The rate of ACC formation differs in response to developmental, hormonal and environmental cues. ACC can be conjugated to three derivatives, metabolized in planta or by rhizobacteria using ACC deaminase, and is transported throughout the plant over short and long distances, remotely leading to ethylene responses. This review highlights some recent advances related to ACC. These include the regulation of ACC synthesis, conjugation and deamination, evidence for a role of ACC as an ethylene-independent signal, short and long range ACC transport, and the identification of a first ACC transporter. Although unraveling the complex mechanism of ACC transport is in its infancy, new questions emerge together with the identification of a first transporter. In the light of the future quest for additional ACC transporters, this review presents perspectives of the novel findings and includes considerations for future research toward applications in agronomy. PMID:28174583

Accumulation and Transport of 1-Aminocyclopropane-1-Carboxylic Acid (ACC) in Plants: Current Status, Considerations for Future Research and Agronomic Applications.

PubMed

Vanderstraeten, Lisa; Van Der Straeten, Dominique

2017-01-01

1-aminocyclopropane-1-carboxylic acid (ACC) is a non-protein amino acid acting as the direct precursor of ethylene, a plant hormone regulating a wide variety of vegetative and developmental processes. ACC is the central molecule of ethylene biosynthesis. The rate of ACC formation differs in response to developmental, hormonal and environmental cues. ACC can be conjugated to three derivatives, metabolized in planta or by rhizobacteria using ACC deaminase, and is transported throughout the plant over short and long distances, remotely leading to ethylene responses. This review highlights some recent advances related to ACC. These include the regulation of ACC synthesis, conjugation and deamination, evidence for a role of ACC as an ethylene-independent signal, short and long range ACC transport, and the identification of a first ACC transporter. Although unraveling the complex mechanism of ACC transport is in its infancy, new questions emerge together with the identification of a first transporter. In the light of the future quest for additional ACC transporters, this review presents perspectives of the novel findings and includes considerations for future research toward applications in agronomy.

Triboelectrification of active pharmaceutical ingredients: week acids and their salts.

PubMed

Fujinuma, Kenta; Ishii, Yuji; Yashihashi, Yasuo; Yonemochi, Estuo; Sugano, Kiyohiko; Tarada, Katsuhide

2015-09-30

The effect of salt formulation on the electrostatic property of active pharmaceutical ingredients was investigated. The electrostatic property of weak acids (carboxylic acids and amide-enole type acid) and their sodium salts was evaluated by a suction-type Faraday cage meter. Free carboxylic acids showed negative chargeability, whereas their sodium salts showed more positive chargeability than the free acids. However, no such trend was observed for amide-enole type acids. Copyright © 2015 Elsevier B.V. All rights reserved.

Enantiomer analysis of chiral carboxylic acids by AIE molecules bearing optically pure aminol groups.

PubMed

Zheng, Yan-Song; Hu, Yu-Jian; Li, Dong-Mi; Chen, Yi-Chang

2010-01-15

Pure enantiomers of carboxylic acids are a class of important biomolecules, chiral drugs, chiral reagents, etc. Analysis of the enantiomers usually needs expensive instrument or complex chiral receptors. However, to develop simple and reliable methods for the enantiomer analysis of acids is difficult. In this paper, chiral recognition of 2,3-dibenzoyltartaric acid and mandelic acid was first carried out by aggregation-induced emission molecules bearing optically pure aminol group, which was easily synthesized. The chiral recognition is not only seen by naked eyes but also measured by fluorophotometer. The difference of fluorescence intensity between the two enantiomers of the acids aroused by the aggregation-induced emission molecules was up to 598. The chiral recognition could be applied to quantitative analysis of enantiomer content of chiral acids. More chiral AIE amines need to be developed for enantiomer analysis of more carboxylic acids.

Ethylene induced shikonin biosynthesis in shoot culture of Lithospermum erythrorhizon.

PubMed

Touno, Kaori; Tamaoka, Jin; Ohashi, Yuko; Shimomura, Koichiro

2005-02-01

Lithospermum erythrorhizon shoots, cultured on phytohormone-free Murashige and Skoog solid medium, produced shikonin derivatives, whereas shoots cultured in well-ventilated petri dishes, produced small amount. Analysis by gas chromatography revealed the presence of ethylene in non-ventilated petri dishes where the shoots, producing shikonin derivatives, were cultured. Therefore, the possible involvement of ethylene in shikonin biosynthesis of shoot cultures was investigated. Treatment of ethylene or the ethylene precursor, 1-aminocyclopropane-1-carboxylic acid, resulted in increasing shikonin derivatives contents in cultured shoots. Silver ion, an ethylene-response inhibitor, or aminoethoxyvinylglycine, an ethylene biosynthesis inhibitor, decreased production of shikonin derivatives in cultured shoots. Our results indicate that ethylene is one of the regulatory elements of shikonin biosynthesis in L. erythrorhizon shoot culture.

Direct esterification of ammonium salts of carboxylic acids

DOEpatents

Halpern, Yuval [Skokie, IL

2003-06-24

A non-catalytic process for producing esters, the process comprising reacting an ammonium salt of a carboxylic acid with an alcohol and removing ammonia from the reaction mixture. Selectivities for the desired ester product can exceed 95 percent.

Oxidative acylation using thioacids

NASA Technical Reports Server (NTRS)

Liu, R.; Orgel, L. E.

1997-01-01

Several important prebiotic reactions, including the coupling of amino acids into polypeptides by the formation of amide linkages, involve acylation. Theae reactions present a challenge to the understanding of prebiotic synthesis. Condensation reactions relying on dehydrating agents are either inefficient in aqueous solution or require strongly acidic conditions and high temperatures. Activated amino acids such as thioester derivatives have therefore been suggested as likely substrates for prebiotic peptide synthesis. Here we propose a closely related route to amide bond formation involving oxidative acylation by thioacids. We find that phenylalanine, leucine and phenylphosphate are acylated efficiently in aqueous solution by thioacetic acid and an oxidizing agent. From a prebiotic point of view, oxidative acylation has the advantage of proceeding efficiently in solution and under mild conditions. We anticipate that oxidative acylation should prove to be a general method for activating carboxylic acids, including amino acids.

Primary structure and nuclear localization of a murine homeodomain protein.

PubMed Central

Kessel, M; Schulze, F; Fibi, M; Gruss, P

1987-01-01

The murine homeobox Hox 1.1 (m6) is the first of a cluster of six boxes on chromosome 6. Using probes and synthetic peptides derived from the Hox 1.1 sequence, we were able to isolate cDNAs and antibodies that allowed us to characterize the product of this homeobox-containing gene. From the open reading frame on the cDNA clone B21, a protein could be predicted, made up of 229 amino acids and having a calculated molecular weight of 25,740. A unique feature of this protein is that it has 15 glutamic acid residues as its carboxyl terminus, which gives it a very hydrophilic and acidic carboxyl terminal structure, most probably folding onto an alpha-helix. A second domain of six amino acids is present on the Hox 1.1 protein, which is conserved in other homeodomain proteins. Antibodies generated against synthetic peptides from the homeobox region were used in the immunoblotting procedure and revealed a major protein band of Mr 31,000 in extracts from 3T3 cells and F9 teratocarcinoma cells induced by retinoic acid and cAMP. The nuclear location of the protein was established by immunofluorescence. The presence of this protein in F9 cell nuclei is in faithful accordance with the kinetics established for the 2.4-kilobase Hox 1.1 transcript during differentiation into parietal endoderm cells. Images PMID:2885847

Nanoparticles modified with multiple organic acids

NASA Technical Reports Server (NTRS)

Luebben, Silvia DeVito (Inventor); Cook, Ronald Lee (Inventor); Wilson, Carolina (Inventor); Meiser, Manfred (Inventor); Myers, Andrew William (Inventor); Smith, Bryan Matthew (Inventor); Elliott, Brian John (Inventor); Kreutzer, Cory (Inventor)

2007-01-01

Surface-modified nanoparticles of boehmite, and methods for preparing the same. Aluminum oxyhydroxide nanoparticles are surface modified by reaction with selected amounts of organic acids. In particular, the nanoparticle surface is modified by reactions with two or more different carboxylic acids, at least one of which is an organic carboxylic acid. The product is a surface modified boehmite nanoparticle that has an inorganic aluminum oxyhydroxide core, or part aluminum oxyhydroxide core and a surface-bonded organic shell. Organic carboxylic acids of this invention contain at least one carboxylic acid group and one carbon-hydrogen bond. One embodiment of this invention provides boehmite nanoparticles that have been surface modified with two or more acids one of which additional carries at least one reactive functional group. Another embodiment of this invention provides boehmite nanoparticles that have been surface modified with multiple acids one of which has molecular weight or average molecular weight greater than or equal to 500 Daltons. Yet, another embodiment of this invention provides boehmite nanoparticles that are surface modified with two or more acids one of which is hydrophobic in nature and has solubility in water of less than 15 by weight. The products of the methods of this invention have specific useful properties when used in mixture with liquids, as filler in solids, or as stand-alone entities.

Nanoparticles modified with multiple organic acids

DOEpatents

Cook, Ronald Lee [Lakewood, CO; Luebben, Silvia DeVito [Golden, CO; Myers, Andrew William [Arvada, CO; Smith, Bryan Matthew [Boulder, CO; Elliott, Brian John [Superior, CO; Kreutzer, Cory [Brighton, CO; Wilson, Carolina [Arvada, CO; Meiser, Manfred [Aurora, CO

2007-07-17

Surface-modified nanoparticles of boehmite, and methods for preparing the same. Aluminum oxyhydroxide nanoparticles are surface modified by reaction with selected amounts of organic acids. In particular, the nanoparticle surface is modified by reactions with two or more different carboxylic acids, at least one of which is an organic carboxylic acid. The product is a surface modified boehmite nanoparticle that has an inorganic aluminum oxyhydroxide core, or part aluminum oxyhydroxide core and a surface-bonded organic shell. Organic carboxylic acids of this invention contain at least one carboxylic acid group and one carbon-hydrogen bond. One embodiment of this invention provides boehmite nanoparticles that have been surface modified with two or more acids one of which additional carries at least one reactive functional group. Another embodiment of this invention provides boehmite nanoparticles that have been surface modified with multiple acids one of which has molecular weight or average molecular weight greater than or equal to 500 Daltons. Yet, another embodiment of this invention provides boehmite nanoparticles that are surface modified with two or more acids one of which is hydrophobic in nature and has solubility in water of less than 15 by weight. The products of the methods of this invention have specific useful properties when used in mixture with liquids, as filler in solids, or as stand-alone entities.

First enantiocontrolled formal synthesis of (+)-neovibsanin B, a neurotrophic diterpenoid.

PubMed

Esumi, Tomoyuki; Mori, Takehiro; Zhao, Ming; Toyota, Masao; Fukuyama, Yoshiyasu

2010-02-19

An enantiocontrolled formal synthesis of (+)-neovibsanin B has been achieved by a sequence that applies an asymmetric 1,4-addition of (H(2)C=CH)(2)Cu(CN)Li(2) to trisubstituted alpha,beta-carboxylic acid derivative 1 to induce the chirality at the C-11 all-carbon quaternary center. Together with a modified Negishi cyclic carbopalladation-carbonylative esterification tandem reaction for constructing the A-ring, the synthesis was completed.

Hit-to-lead optimization of pyrrolo[1,2-a]quinoxalines as novel cannabinoid type 1 receptor antagonists.

PubMed

Szabó, György; Kiss, Róbert; Páyer-Lengyel, Dóra; Vukics, Krisztina; Szikra, Judit; Baki, Andrea; Molnár, László; Fischer, János; Keseru, György M

2009-07-01

Hit-to-lead optimization of a novel series of N-alkyl-N-[2-oxo-2-(4-aryl-4H-pyrrolo[1,2-a]quinoxaline-5-yl)-ethyl]-carboxylic acid amides, derived from a high throughput screening (HTS) hit, are described. Subsequent optimization led to identification of in vitro potent cannabinoid 1 receptor (CB1R) antagonists representing a new class of compounds in this area.

ESTIMATION OF CARBOXYLIC ACID ESTER HYDROLYSIS RATE CONSTANTS

EPA Science Inventory

SPARC chemical reactivity models were extended to calculate hydrolysis rate constants for carboxylic acid esters from molecular structure. The energy differences between the initial state and the transition state for a molecule of interest are factored into internal and external...

Reactive Capture of Gold Nanoparticles by Strongly Physisorbed Monolayers on Graphite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wei, Xiaoliang; Tong, Wenjun; Fidler, Vlastimil

2012-12-01

Anthracene Diels Alder adducts (DAa) bearing two long side chains (H-(CH2)22O(CH2)6OCH2-) at the 1- and 5-positions form self-assembled monolayers (SAMs) at the phenyloctane - highly oriented pyrolytic graphite (HOPG) interface. The long DAa side chains promote strong physisorption of the monolayer to HOPG and maintain the monolayer morphology upon rinsing or incubation in ethanol and air-drying of the substrate. Incorporating a carboxylic acid group on the DAa core enables capture of 1 - 4 nm diameter gold nanoparticles (AuNP) provided (i) the monolayer containing DAa-carboxylic acids is treated with Cu2+ ions and (ii) the organic coating on the AuNP containsmore » carboxylic acids (11-mercaptoundecanoic acid, MUA-AuNP). AuNP capture by the monolayer proceeds with formation of Cu2+ - carboxylate coordination complexes. The captured AuNP appear as mono- and multi-layered clusters at high coverage on HOPG. The surface density of the captured AuNPs can be adjusted from AuNP multi-layers to isolated AuNPs by varying incubation times, MUA-AuNP concentration, the number density of carboxylic acids in the monolayer, the number of MUA per AuNP, and the post-incubation treatments.« less

Measuring the concentration of carboxylic acid groups in torrefied spruce wood.

PubMed

Khazraie Shoulaifar, Tooran; Demartini, Nikolai; Ivaska, Ari; Fardim, Pedro; Hupa, Mikko

2012-11-01

Torrefaction is moderate thermal treatment (∼200-300°C) to improve the energy density, handling and storage properties of biomass fuels. In biomass, carboxylic sites are partially responsible for its hygroscopic. These sites are degraded to varying extents during torrefaction. In this paper, we apply methylene blue sorption and potentiometric titration to measure the concentration of carboxylic acid groups in spruce wood torrefied for 30min at temperatures between 180 and 300°C. The results from both methods were applicable and the values agreed well. A decrease in the equilibrium moisture content at different humidity was also measured for the torrefied wood samples, which is in good agreement with the decrease in carboxylic acid sites. Thus both methods offer a means of directly measuring the decomposition of carboxylic groups in biomass during torrefaction as a valuable parameter in evaluating the extent of torrefaction which provides new information to the chemical changes occurring during torrefaction. Copyright © 2012 Elsevier Ltd. All rights reserved.

A Quick and Simple Conversion of Carboxylic Acids into Their Anilides of Heating with Phenyl Isothiocyanate.

ERIC Educational Resources Information Center

Ram, Ram N.; And Others

1983-01-01

Converting carboxylic acids into their anilides, which usually involves preparation of acid chloride or mixed anhydride followed by treatment with aniline, is tedious and/or time-consuming. A quick and easier procedure, using phenyl isothiocyanate, is provided. Reactions involved and a summary table of results are included. (JN)

Identification of the Phenol Functionality in Deprotonated Monomeric and Dimeric Lignin Degradation Products via Tandem Mass Spectrometry Based on Ion-Molecule Reactions with Diethylmethoxyborane

NASA Astrophysics Data System (ADS)

Zhu, Hanyu; Max, Joann P.; Marcum, Christopher L.; Luo, Hao; Abu-Omar, Mahdi M.; Kenttämaa, Hilkka I.

2016-11-01

Conversion of lignin into smaller molecules provides a promising alternate and sustainable source for the valuable chemicals currently derived from crude oil. Better understanding of the chemical composition of the resulting product mixtures is essential for the optimization of such conversion processes. However, these mixtures are complex and contain isomeric molecules with a wide variety of functionalities, which makes their characterization challenging. Tandem mass spectrometry based on ion-molecule reactions has proven to be a powerful tool in functional group identification and isomer differentiation for previously unknown compounds. This study demonstrates that the identification of the phenol functionality, the most commonly observed functionality in lignin degradation products, can be achieved via ion-molecule reactions between diethylmethoxyborane (DEMB) and the deprotonated analyte in the absence of strongly electron-withdrawing substituents in the ortho- and para-positions. Either a stable DEMB adduct or an adduct that has lost a methanol molecule (DEMB adduct-MeOH) is formed for these ions. Deprotonated phenols with an adjacent phenol or hydroxymethyl functionality or a conjugated carboxylic acid functionality can be identified based on the formation of DEMB adduct-MeOH. Deprotonated compounds not containing the phenol functionality and phenols containing an electron-withdrawing ortho- or para-substituent were found to be unreactive toward diethylmethoxyborane. Hence, certain deprotonated isomeric compounds with phenol and carboxylic acid, aldehyde, carboxylic acid ester, or nitro functionalities can be differentiated via these reactions. The above mass spectrometry method was successfully coupled with high-performance liquid chromatography for the analysis of a complex biomass degradation mixture.

Intramolecular Tsuji-Trost-type Allylation of Carboxylic Acids: Asymmetric Synthesis of Highly π-Allyl Donative Lactones.

PubMed

Suzuki, Yusuke; Seki, Tomoaki; Tanaka, Shinji; Kitamura, Masato

2015-08-05

Tsuji-Trost-type asymmetric allylation of carboxylic acids has been realized by using a cationic CpRu complex with an axially chiral picolinic acid-type ligand (Cl-Naph-PyCOOH: naph = naphthyl, py = pyridine). The carboxylic acid and allylic alcohol intramolecularly condense by the liberation of water without stoichiometric activation of either nucleophile or electrophile part, thereby attaining high atom- and step-economy, and low E factor. This success can be ascribed to the higher reactivity of allylic alcohols as compared with the allyl ester products in soft Ru/hard Brønstead acid combined catalysis, which can function under slightly acidic conditions unlike the traditional Pd-catalyzed system. Detailed analysis of the stereochemical outcome of the reaction using an enantiomerically enriched D-labeled substrate provides an intriguing view of enantioselection.

Simple quantification of surface carboxylic acids on chemically oxidized multi-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Gong, Hyejin; Kim, Seong-Taek; Lee, Jong Doo; Yim, Sanggyu

2013-02-01

The surface of multi-walled carbon nanotube (MWCNT) was chemically oxidized using nitric acid and sulfuric-nitric acid mixtures. Thermogravimetric analysis, transmission electron microscopy and infrared spectroscopy revealed that the use of acid mixtures led to higher degree of oxidation. More quantitative identification of surface carboxylic acids was carried out using X-ray photoelectron spectroscopy (XPS) and acid-base titration. However, these techniques are costly and require very long analysis times to promptly respond to the extent of the reaction. We propose a much simpler method using pH measurements and pre-determined pKa value in order to estimate the concentration of carboxylic acids on the oxidized MWCNT surfaces. The results from this technique were consistent with those obtained from XPS and titration, and it is expected that this simple quantification method can provide a cheap and fast way to monitor and control the oxidation reaction of MWCNT.

Molecular design and synthesis of functional photothermopolymers from hydroxyl benzoic acids

NASA Astrophysics Data System (ADS)

Tong, Xiao; Gu, Jiangnan; Wang, Liyuan; Zou, Yingquan; Yu, Shangxian

2000-06-01

The most applicable hydroxyl benzoic acid monomers were optimized to synthesize the thermolysis-decarboxylation polymers according to the relative results of TG analysis of hydroxyl benzoic acids, their 13C-NMR spectra analyses and their quantum chemistry calculation with AB-INITIO method. On the basis of the empirical rule -- M/A value rule, while phenols with high M/A value and hydroxyl benzoic acids were both cocondensed with formaldehyde at proper ratio, the novolak resin with carboxyl groups used as a thermal imaging material could be obtained. In the presence of an acid catalyst, such as oxalic acid, a hydroxyl benzoic acid could be additionally polymerized with divinyl benzene (DVB) to synthesize another kind of polymer with not only carboxyl groups but also phenolic hydroxyl groups. The thermal imaging mechanisms of these polymers with carboxyl groups were discussed in the paper.

Atmospheric chemistry of carboxylic acids: microbial implication versus photochemistry

NASA Astrophysics Data System (ADS)

Vaïtilingom, M.; Charbouillot, T.; Deguillaume, L.; Maisonobe, R.; Parazols, M.; Amato, P.; Sancelme, M.; Delort, A.-M.

2011-02-01

Clouds are multiphasic atmospheric systems in which the dissolved organic compounds, dominated by carboxylic acids, are subject to multiple chemical transformations in the aqueous phase. Among them, solar radiation, by generating hydroxyl radicals (•OH), is considered as the main catalyzer of the reactivity of organic species in clouds. We investigated to which extent the active biomass existing in cloud water represents an alternative route to the chemical reactivity of carboxylic acids. Pure cultures of seventeen bacterial strains (Arthrobacter, Bacillus, Clavibacter, Frigoribacterium, Pseudomonas, Sphingomonas and Rhodococcus), previously isolated from cloud water and representative of the viable community of clouds were first individually incubated in two artificial bulk cloud water solutions at 17 °C and 5 °C. These solutions mimicked the chemical composition of cloud water from "marine" and "continental" air masses, and contained the major carboxylic acids existing in the cloud water (i.e. acetate, formate, succinate and oxalate). The concentrations of these carboxylic compounds were monitored over time and biodegradation rates were determined. In average, they ranged from 2 ×10-19 for succinate to 1 × 10-18 mol cell-1 s-1 for formate at 17 °C and from 4 × 10-20 for succinate to 6 × 10-19 mol cell-1 s-1 for formate at 5 °C, with no significant difference between "marine" and "continental" media. In parallel, irradiation experiments were also conducted in these two artificial media to compare biodegradation and photodegradation of carboxylic compounds. To complete this comparison, the photodegradation rates of carboxylic acids by •OH radicals were calculated from literature data. Inferred estimations suggested a significant participation of microbes to the transformation of carboxylic acids in cloud water, particularly for acetate and succinate (up to 90%). Furthermore, a natural cloud water sample was incubated (including its indigenous microflora); the rates of biodegradation were determined and compared to the photodegradation rates involving •OH radicals. The biodegradation rates in "natural" and "artificial" cloud water were in the same order of magnitude; this confirms the significant role of the active biomass in the aqueous reactivity of clouds.

Approaches for the Analysis of Chlorinated Lipids

PubMed Central

Wang, Wen-yi; Albert, Carolyn J.; Ford, David A.

2013-01-01

Leukocytes are key cellular mediators of human diseases through their role in inflammation. Identifying unique molecules produced by leukocytes may provide new biomarkers and mechanistic insights into the role of leukocytes in disease. Chlorinated lipids are generated as a result of myeloperoxidase-containing leukocyte-derived hypochlorous acid targeting the vinyl ether bond of plasmalogens. The initial product of this reaction is α-chlorofatty aldehyde. α -Chlorofatty aldehyde is both oxidized to α-chlorofatty acid and reduced to α-chlorofatty alcohol by cellular metabolism. This review focuses on the separation techniques and quantitative analysis for these chlorinated lipids. For α-chlorofatty acid the negative charge of carboxylic acids is exploited to detect the chlorinated lipid species of these acids by electrospray ionization mass spectrometry in the negative ion mode. In contrast, α-chlorofatty aldehyde and α-chlorofatty alcohol are converted to pentafluorobenzyl oxime and pentafluorobenzoyl ester derivatives, which are detected by negative ion-chemical ionization mass spectrometry. These two detection methods coupled with the use of stable isotope internal standards and either liquid chromatography or gas chromatography provide highly sensitive analytical approaches to measure these novel lipids. PMID:24056259

Performance, kinetics, and equilibrium of methylene blue adsorption on biochar derived from eucalyptus saw dust modified with citric, tartaric, and acetic acids.

PubMed

Sun, Lei; Chen, Dongmei; Wan, Shungang; Yu, Zebin

2015-12-01

Biochar derived from eucalyptus saw dust modified with citric, tartaric, and acetic acids at low temperatures was utilized as adsorbent to remove methylene blue (MB) from aqueous solutions. Fourier transform infrared spectroscopy analysis showed that the carboxyl group was introduced on the biochar surface. Adsorption experiment data indicated that eucalyptus saw dust modified with citric acid showed higher MB adsorption efficiency than that modified with tartaric and acetic acids. Pseudo-second-order kinetics was the most suitable model for describing MB adsorption on biochar compared with pseudo-first-order, Elovich, and intraparticle diffusion models. The calculated values of ΔG(0) and ΔH(0) indicated the spontaneous and endothermic nature of the adsorption process. MB adsorption on biochar followed the Langmuir isotherm. The maximum adsorption capacities for eucalyptus saw dust modified with citric, tartaric, and acetic acids were 178.57, 99.01, and 29.94 mg g(-1), respectively, at 35°C. Copyright © 2015 Elsevier Ltd. All rights reserved.

Structural characterization of 1,3-propanedithiols that feature carboxylic acids: Homologues of mercury chelating agents ✩

PubMed Central

Sattler, Wesley; Palmer, Joshua H.; Bridges, Christy C.; Joshee, Lucy; Zalups, Rudolfs K.; Parkin, Gerard

2013-01-01

The molecular structures of a series of 1,3-propanedithiols that contain carboxylic acid groups, namely rac- and meso-2,4-dimercaptoglutaric acid (H4DMGA) and 2-carboxy-1,3-propanedithiol (H3DMCP), have been determined by X-ray diffraction. Each compound exhibits two centrosymmetric intermolecular hydrogen bonding interactions between pairs of carboxylic acid groups, which result in a dimeric structure for H3DMCP and a polymeric tape-like structure for rac- and meso-H4DMGA. Significantly, the hydrogen bonding motifs observed for rac- and meso-H4DMGA are very different to those observed for the 1,2-dithiol, rac-2,3-dimercaptosuccinic acid (rac-H4DMSA), in which the two oxygen atoms of each carboxylic acid group hydrogen bond to two different carboxylic acid groups, thereby resulting in a hydrogen bonded sheet-like structure rather than a tape. Density functional theory calculations indicate that 1,3-dithiolate coordination to mercury results in larger S–Hg–S bond angles than does 1,2-dithiolate coordination, but these angles are far from linear. As such, κ2-S2 coordination of these dithiolate ligands is expected to be associated with mercury coordination numbers of greater than two. In vivo studies demonstrate that both rac-H4DMGA and H3DMCP reduce the renal burden of mercury in rats, although the compounds are not as effective as either 2,3-dimercaptopropane-1-sulfonic acid (H3DMPS) or meso-H4DMSA. PMID:24187425

Facile preparation of oxazole-4-carboxylates and 4-ketones from aldehydes using 3-oxazoline-4-carboxylates as intermediates.

PubMed

Murai, Kenichi; Takahara, Yusuke; Matsushita, Tomoyo; Komatsu, Hideyuki; Fujioka, Hiromichi

2010-08-06

A novel 2-step synthesis of oxazole-4-carboxylates from aldehydes was developed, which is characterized by the utilization of 3-oxazoline-4-carboxylates as synthetic intermediates. The facile preparation of 4-keto-oxazole derivatives from 3-oxazoline-4-carboxylates based on their interesting reactivity toward Grignard reagents is also described.

Screening of nerve agent degradation products by MALDI-TOFMS.

PubMed

Shu, You-Ren; Su, An-Kai; Liu, Ju-Tsung; Lin, Cheng-Huang

2006-07-01

A novel method for the rapid screening of degradation products derived from nerve agents by matrix-assisted laser desorption ionization time-of-flight mass spectrometry is described. Five standard products were selected as model compounds, including isopropyl methylphosphonic acid (IMPA), pinacolyl methylphosphonic acid (PMPA), ethyl methylphosphonic acid (EMPA), isobutyl methylphosphonic acid (i-BuMPA), and cyclohexyl methylphosphonic acid (CHMPA), which are degradation products of Sarin (GB), Soman (GD), VX, Russian VX (RVX), and GF, respectively. For comparison, CHCA (alpha-cyano-4-hydroxycinnamic acid) and DCCA (7-(diethylamino)coumarin-3-carboxylic acid) were used as the MALDI-matrix when the third harmonic generation (355 nm) of a Nd:YAG laser and a hydrogen Raman laser (multifrequency laser) were used, respectively. The method permitted the five nerve agent degradation products to be screened rapidly and successfully, suggesting that it has the potential for use as a routine monitoring tool.

Soft Ultraviolet (UV) Photopatterning and Metallization of Self-Assembled Monolayers (SAMs) Formed from the Lipoic Acid Ester of α-Hydroxy-1-acetylpyrene: The Generality of Acid-Catalyzed Removal of Thiol-on-Gold SAMs using Soft UV Light.

PubMed

Pukenas, Laurynas; Prompinit, Panida; Nishitha, Boda; Tate, Daniel J; Singh, N D Pradeep; Wälti, Christoph; Evans, Stephen D; Bushby, Richard J

2017-05-31

Under a layer of 0.1 M HCl in isopropanol, soft ultraviolet (UV) (365 nm) photolysis of the thiol-on-gold self-assembled monolayer (SAM) derived from the lipoic acid ester of α-hydroxy-1-acetylpyrene results in the expected removal of the acetylpyrene protecting group. When photolyzing through a mask, this can be used to produce a patterned surface and, at a controlled electrochemical potential, it is then possible to selectively and reversibly electrodeposit copper on the photolyzed regions. Rather surprisingly, under these photolysis conditions, there is not only the expected photodeprotection of the ester but also partial removal of the lipoic acid layer which has been formed. In further studies, it is shown that this type of acid-catalyzed photoremoval of SAM layers by soft UV is a rather general phenomenon and results in the partial removal of the thiol-on-gold SAM layers derived from other ω-thiolated carboxylic acids. However, this phenomenon is chain-length dependent. Under conditions in which there is a ∼60% reduction in the thickness of the SAM derived from dithiobutyric acid, the SAM derived from mercaptoundecanoic acid is almost unaffected. The process by which the shorter-chain SAM layers are partially removed is not fully understood because these compounds do not absorb significantly in the 365 nm region of the spectrum! Significantly, this study shows that acid catalysis photolysis of thiol-on-gold SAMs needs to be used with caution.

Integrated production of lignin containing cellulose nanocrystals (LCNC) and nanofibrils (LCNF) using an easily recyclable di-carboxylic acid

Treesearch

Huiyang Bian; Liheng Chen; Hongqi Dai; J.Y. Zhu

2017-01-01

Here we demonstrate di-carboxylic acid hydrolysis for the integrated production of lignin containing cellulose nanocrystals (LCNC) and nanofibrils (LCNF) using two unbleached hardwood chemical pulps of lignin contents of 3.9 and 17.2%. Acid hydrolysis experiments used maleic acid solution of 60 wt% concentration at 120°C for 120 min under ambient pressure. Yields of...

Merging photoredox and nickel catalysis: decarboxylative cross-coupling of carboxylic acids with vinyl halides.

PubMed

Noble, Adam; McCarver, Stefan J; MacMillan, David W C

2015-01-21

Decarboxylative cross-coupling of alkyl carboxylic acids with vinyl halides has been accomplished through the synergistic merger of photoredox and nickel catalysis. This new methodology has been successfully applied to a variety of α-oxy and α-amino acids, as well as simple hydrocarbon-substituted acids. Diverse vinyl iodides and bromides give rise to vinylation products in high efficiency under mild, operationally simple reaction conditions.

The molecular assembly of the ionic liquid/aliphatic carboxylic acid/aliphatic amine as effective and safety transdermal permeation enhancers.

PubMed

Kubota, Koji; Shibata, Akira; Yamaguchi, Toshikazu

2016-04-30

In spite of numerous advantages, transdermal drug delivery systems are unfeasible for most drugs because of the barrier effect of the stratum corneum. Ionic liquids were recently used to enhance transdermal drug delivery by improving drug solubility. In the present study, safe and effective ionic liquids for transdermal absorption were obtained as salts generated by a neutralization reaction between highly biocompatible aliphatic carboxylic acids (octanoic acid or isostearic acid) and aliphatic amines (diisopropanolamine or triisopropanolamine) (Medrx Co., Ltd., 2009). The mechanism of skin permeability enhancement by ionic liquids was investigated by hydrophilic phenol red and hydrophobic tulobuterol. Further, the skin permeation enhancing effect was remarkably superior in the acid excess state rather than the neutralization state. Infrared absorption spectrum analysis confirmed that ionic liquids/aliphatic carboxylic acid/aliphatic amine are coexisting at all mixing states. In the acid excess state, ionic liquids interact with aliphatic carboxylic acids via hydrogen bonds. Thus, the skin permeation enhancing effect is not caused by the ionic liquid alone. The "liquid salt mixture," referred to as a complex of ingredients coexisting with ionic liquids, forms a molecular assembly incorporating hydrophilic drug. This molecular assembly was considered an effective and safety enhancer of transdermal drug permeation. Copyright © 2016. Published by Elsevier B.V.

Supramolecular hydrogen-bonding patterns in 1:1 cocrystals of 5-fluorouracil with 4-methylbenzoic acid and 3-nitrobenzoic acid.

PubMed

Mohana, Marimuthu; Muthiah, Packianathan Thomas; McMillen, Colin D

2017-03-01

The design of a pharmaceutical cocrystal is based on the identification of specific hydrogen-bond donor and acceptor groups in active pharmaceutical ingredients (APIs) in order to choose a `complementary interacting' molecule that can act as an efficient coformer. 5-Fluorouracil (5FU) is a pyrimidine derivative with two N-H donors and C=O acceptors and shows a diversity of hydrogen-bonding motifs. Two 1:1 cocrystals of 5-fluorouracil (5FU), namely 5-fluorouracil-4-methylbenzoic acid (5FU-MBA), C 4 H 3 FN 2 O 2 ·C 8 H 8 O 2 , (I), and 5-fluorouracil-3-nitrobenzoic acid (5FU-NBA), C 4 H 3 FN 2 O 2 ·C 7 H 5 NO 4 , (II), have been prepared and characterized by single-crystal X-ray diffraction. In (I), the MBA molecules form carboxylic acid dimers [R 2 2 (8) homosynthon]. Similarly, the 5FU molecules form two types of base pair via a pair of N-H...O hydrogen bonds [R 2 2 (8) homosynthon]. In (II), 5FU interacts with the carboxylic acid group of NBA via N-H...O and O-H...O hydrogen bonds, generating an R 2 2 (8) ring motif (heterosynthon). Furthermore, the 5FU molecules form base pairs [R 2 2 (8) homosynthon] via N-H...O hydrogen bonds. Both of the crystal structures are stabilized by C-H...F interactions.

Aryliminopropadienone-C-Amidoketenimine- Amidinoketene-2-Aminoquinolone Cascades and the Ynamine-Isocyanate Reaction.

PubMed

Wentrup, Curt; Rao, V. V. Ramana; Frank, Wilhelm; Fulloon, Belinda E.; Moloney, Daniel W. J.; Mosandl, Thomas

1999-05-14

Imidoylketenes 11 and oxoketenimines 12 are generated by flash vacuum thermolysis of Meldrum's acid derivatives 9, pyrrolediones 17 and 18, and triazole 19 and are observed by IR spectroscopy. Ketenimine-3-carboxylic acid esters 12a are isolable at room temperature. Ketenes 11 and ketenimines 12 undergo rapid interconversion in the gas phase, and the ketenes cyclize to 4-quinolones 13. When using an amine leaving group in Meldrum's acid derivatives 9c, the major reaction products are aryliminopropadienones, ArN=C=C=C=O (15). The latter react with 1 equiv of nucleophile to produce ketenimines 12 and with 2 equiv to afford malonic acid imide derivatives 16. N-Arylketenimine-C-carboxamides 12c cyclize to quinolones 13c via the transient amidinoketenes 11c at temperatures of 25-40 degrees C. This implies rapid interconversion of ketenes and ketenimines by a 1,3-shift of the dimethylamino group, even at room temperature. This interconversion explains previously poorly understood outcomes of the ynamine-isocyanate reaction. The solvent dependence of the tautomerism of 4-quinolones/4-quinolinols is discussed. Rotational barriers of NMe(2) groups in amidoketenimines 12c and malonioc amides and amidines 16 (24) are reported.

Effect of Producing Different Phenazines on Bacterial Fitness and Biological Control in Pseudomonas chlororaphis 30-84

PubMed Central

Yu, Jun Myoung; Wang, Dongping; Pierson, Leland S.; Pierson, Elizabeth A.

2018-01-01

Pseudomonas chlororaphis 30-84 is a biological control agent selected for its ability to suppress diseases caused by fungal pathogens. P. chlororaphis 30-84 produces three phenazines: phenazine-1-carboxylic acid (PCA), 2-hydroxy-phenazine-1-carboxylic acid (2OHPCA) and a small amount of 2-hydroxy-phenazine (2OHPHZ), and these are required for fungal pathogen inhibition and wheat rhizosphere competence. The two, 2-hydroxy derivatives are produced from PCA via the activity of a phenazine-modifying enzyme encoded by phzO. In addition to the seven biosynthetic genes responsible for the production of PCA, many other Pseudomonas strains possess one or more modifying genes, which encode enzymes that act independently or together to convert PCA into other phenazine derivatives. In order to understand the fitness effects of producing different phenazines, we constructed isogenic derivatives of P. chlororaphis 30-84 that differed only in the type of phenazines produced. Altering the type of phenazines produced by P. chlororaphis 30-84 enhanced the spectrum of fungal pathogens inhibited and altered the degree of take-all disease suppression. These strains also differed in their ability to promote extracellular DNA release, which may contribute to the observed differences in the amount of biofilm produced. All derivatives were equally important for survival over repeated plant/harvest cycles, indicating that the type of phenazines produced is less important for persistence in the wheat rhizosphere than whether or not cells produce phenazines. These findings provide a better understanding of the effects of different phenazines on functions important for biological control activity with implications for applications that rely on introduced or native phenazine producing populations. PMID:29422787

Interaction of cruciferous phytoanticipins with plant fungal pathogens: indole glucosinolates are not metabolized but the corresponding desulfo-derivatives and nitriles are.

PubMed

Pedras, M Soledade C; Hossain, Sajjad

2011-12-01

Glucosinolates represent a large group of plant natural products long known for diverse and fascinating physiological functions and activities. Despite the relevance and huge interest on the roles of indole glucosinolates in plant defense, little is known about their direct interaction with microbial plant pathogens. Toward this end, the metabolism of indolyl glucosinolates, their corresponding desulfo-derivatives, and derived metabolites, by three fungal species pathogenic on crucifers was investigated. While glucobrassicin, 1-methoxyglucobrassicin, 4-methoxyglucobrassicin were not metabolized by the pathogenic fungi Alternaria brassicicola, Rhizoctonia solani and Sclerotinia sclerotiorum, the corresponding desulfo-derivatives were metabolized to indolyl-3-acetonitrile, caulilexin C (1-methoxyindolyl-3-acetonitrile) and arvelexin (4-methoxyindolyl-3-acetonitrile) by R. solani and S. sclerotiorum, but not by A. brassicicola. That is, desulfo-glucosinolates were metabolized by two non-host-selective pathogens, but not by a host-selective. Indolyl-3-acetonitrile, caulilexin C and arvelexin were metabolized to the corresponding indole-3-carboxylic acids. Indolyl-3-acetonitriles displayed higher inhibitory activity than indole desulfo-glucosinolates. Indolyl-3-methanol displayed antifungal activity and was metabolized by A. brassicicola and R. solani to the less antifungal compounds indole-3-carboxaldehyde and indole-3-carboxylic acid. Diindolyl-3-methane was strongly antifungal and stable in fungal cultures, but ascorbigen was not stable in solution and displayed low antifungal activity; neither compound appeared to be metabolized by any of the three fungal species. The cell-free extracts of mycelia of A. brassicicola displayed low myrosinase activity using glucobrassicin as substrate, but myrosinase activity was not detectable in mycelia of either R. solani or S. sclerotiorum. Copyright © 2011 Elsevier Ltd. All rights reserved.

Synthesis and biological activity of alkynoic acids derivatives against mycobacteria

PubMed Central

Vilchèze, Catherine; Leung, Lawrence W.; Bittman, Robert; Jacobs, William R.

2015-01-01

2-alkynoic acids have bactericidal activity against Mycobacterium smegmatis but their activity fall sharply as the length of the carbon chain increased. In this study, derivatives of 2- alkynoic acids were synthesized and tested against fast- and slow-growing mycobacteria. Their activity was first evaluated in M. smegmatis against their parental 2-alkynoic acids, as well as isoniazid, a first-line antituberculosis drug. The introduction of additional unsaturation or heteroatoms into the carbon chain enhanced the antimycobacterial activity of longer chain alkynoic acids (more than 19 carbons long). In contrast, although the modification of the carboxylic group did not improve the antimycobacterial activity, it significantly reduced the toxicity of the compounds against eukaryotic cells. Importantly, 4-(alkylthio)but-2-ynoic acids, had better bactericidal activity than the parental 2-alkynoic acids and on a par with isoniazid against the slow-grower Mycobacterium bovis BCG. These compounds had also low toxicity against eukaryotic cells, suggesting that they could be potential therapeutic agents against other types of topical mycobacterial infections causing skin diseases including Mycobacterium abscessus, Mycobacterium ulcerans, and Mycobacterium leprae. Moreover, they provide a possible scaffold for future drug development. PMID:26256431

Validation of a method for quantitation of the clopidogrel active metabolite, clopidogrel, clopidogrel carboxylic acid, and 2-oxo-clopidogrel in feline plasma.

PubMed

Lyngby, Janne G; Court, Michael H; Lee, Pamela M

2017-08-01

The clopidogrel active metabolite (CAM) is unstable and challenging to quantitate. The objective was to validate a new method for stabilization and quantitation of CAM, clopidogrel, and the inactive metabolites clopidogrel carboxylic acid and 2-oxo-clopiodgrel in feline plasma. Two healthy cats administered clopidogrel to demonstrate assay in vivo utility. Stabilization of CAM was achieved by adding 2-bromo-3'methoxyacetophenone to blood tubes to form a derivatized CAM (CAM-D). Method validation included evaluation of calibration curve linearity, accuracy, and precision; within and between assay precision and accuracy; and compound stability using spiked blank feline plasma. Analytes were measured by high performance liquid chromatography with tandem mass spectrometry. In vivo utility was demonstrated by a pharmacokinetic study of cats given a single oral dose of 18.75mg clopidogrel. The 2-oxo-clopidogrel metabolite was unstable. Clopidogrel, CAM-D, and clopidogrel carboxylic acid appear stable for 1 week at room temperature and 9 months at -80°C. Standard curves showed linearity for CAM-D, clopidogrel, and clopidogrel carboxylic acid (r > 0.99). Between assay accuracy and precision was ≤2.6% and ≤7.1% for CAM-D and ≤17.9% and ≤11.3% for clopidogrel and clopidogrel carboxylic acid. Within assay precision for all three compounds was ≤7%. All three compounds were detected in plasma from healthy cats receiving clopidogrel. This methodology is accurate and precise for simultaneous quantitation of CAM-D, clopidogrel, and clopidogrel carboxylic acid in feline plasma but not 2-oxo-clopidogrel. Validation of this assay is the first step to more fully understanding the use of clopidogrel in cats. Copyright © 2017 Elsevier B.V. All rights reserved.

A non-cytotoxic N-dehydroabietylamine derivative with potent antimalarial activity.

PubMed

Sadashiva, Maralinganadoddi P; Gowda, Raghavendra; Wu, Xianzhu; Inamdar, Gajanan S; Kuzu, Omer F; Rangappa, Kanchugarakoppal S; Robertson, Gavin P; Gowda, D Channe

2015-08-01

Malaria caused by the Plasmodium parasites continues to be an enormous global health problem owing to wide spread drug resistance of parasites to many of the available antimalarial drugs. Therefore, development of new classes of antimalarial agents is essential to effectively treat malaria. In this study, the efficacy of naturally occurring diterpenoids, dehydroabietylamine and abietic acid, and their synthetic derivatives was assessed for antimalarial activity. Dehydroabietylamine and its N-trifluoroacetyl, N-tribromoacetyl, N-benzoyl, and N-benzyl derivatives showed excellent activity against P. falciparum parasites with IC50 values of 0.36 to 2.6 µM. Interestingly, N-dehydroabietylbenzamide showed potent antimalarial activity (IC50 0.36), and negligible cytotoxicity (IC50 >100 µM) to mammalian cells; thus, this compound can be an important antimalarial drug. In contrast, abietic acid was only marginally effective, exhibiting an IC50 value of ~82 µM. Several carboxylic group-derivatives of abietic acid were moderately active with IC50 values of ~8.2 to ~13.3 µM. These results suggest that a detailed understanding of the structure-activity relationship of abietane diterpenoids might provide strategies to exploit this class of compounds for malaria treatment. Copyright © 2015 Elsevier Inc. All rights reserved.

Assembly of acid-functionalized single-walled carbon nanotubes at oil/water interfaces.

PubMed

Feng, Tao; Hoagland, David A; Russell, Thomas P

2014-02-04

The efficient segregation of water-soluble, acid-functionalized, single-walled carbon nanotubes (SWCNTs) at the oil/water interface was induced by dissolving low-molecular-weight amine-terminated polystyrene (PS-NH2) in the oil phase. Salt-bridge interactions between carboxylic acid groups of SWCNTs and amine groups of PS drove the assembly of SWCNTs at the interface, monitored by pendant drop tensiometry and laser scanning confocal microscopy. The impact of PS end-group functionality, PS and SWCNT concentrations, and the degree of SWCNT acid modification on the interfacial activity was assessed, and a sharp drop in interfacial tension was observed above a critical SWCNT concentration. Interfacial tensions were low enough to support stable oil/water emulsions. Further experiments, including potentiometric titrations and the replacement of SWCNTs by other carboxyl-containing species, demonstrated that the interfacial tension drop reflects the loss of SWCNT charge as the pH falls near/below the intrinsic carboxyl dissociation constant; species lacking multivalent carboxylic acid groups are inactive. The trapped SWCNTs appear to be neither ordered nor oriented.

Heterogeneous Coordination Environments in Lithium-Neutralized Ionomers Identified Using 1H and 7Li MAS NMR

PubMed Central

Alam, Todd M.; Jenkins, Janelle E.; Bolintineanu, Dan S.; Stevens, Mark J.; Frischknecht, Amalie L.; Buitrago, C. Francisco; Winey, Karen I.; Opper, Kathleen L.; Wagener, Kenneth B.

2012-01-01

The carboxylic acid proton and the lithium coordination environments for precise and random Li-neutralized polyethylene acrylic acid P(E-AA) ionomers were explored using high speed solid-state 1H and 7Li MAS NMR. While the 7Li NMR revealed only a single Li coordination environment, the chemical shift temperature variation was dependent on the precise or random nature of the P(E-AA) ionomer. The 1H MAS NMR revealed two different carboxylic acid proton environments in these materials. By utilizing 1H-7Li rotational echo double resonance (REDOR) MAS NMR experiments, it was demonstrated that the proton environments correspond to different average 1H-7Li distances, with the majority of the protonated carboxylic acids having a close through space contact with the Li. Molecular dynamics simulations suggest that the shortest 1H-7Li distance corresponds to un-neutralized carboxylic acids directly involved in the coordination environment of Li clusters. These solid-state NMR results show that heterogeneous structural motifs need to be included when developing descriptions of these ionomer materials.

Historic records of organic compounds from a high Alpine glacier: influences of biomass burning, anthropogenic emissions, and dust transport

NASA Astrophysics Data System (ADS)

Müller-Tautges, C.; Eichler, A.; Schwikowski, M.; Pezzatti, G. B.; Conedera, M.; Hoffmann, T.

2016-01-01

Historic records of α-dicarbonyls (glyoxal, methylglyoxal), carboxylic acids (C6-C12 dicarboxylic acids, pinic acid, p-hydroxybenzoic acid, phthalic acid, 4-methylphthalic acid), and ions (oxalate, formate, calcium) were determined with annual resolution in an ice core from Grenzgletscher in the southern Swiss Alps, covering the time period from 1942 to 1993. Chemical analysis of the organic compounds was conducted using ultra-high-performance liquid chromatography (UHPLC) coupled to electrospray ionization high-resolution mass spectrometry (ESI-HRMS) for dicarbonyls and long-chain carboxylic acids and ion chromatography for short-chain carboxylates. Long-term records of the carboxylic acids and dicarbonyls, as well as their source apportionment, are reported for western Europe. This is the first study comprising long-term trends of dicarbonyls and long-chain dicarboxylic acids (C6-C12) in Alpine precipitation. Source assignment of the organic species present in the ice core was performed using principal component analysis. Our results suggest biomass burning, anthropogenic emissions, and transport of mineral dust to be the main parameters influencing the concentration of organic compounds. Ice core records of several highly correlated compounds (e.g., p-hydroxybenzoic acid, pinic acid, pimelic, and suberic acids) can be related to the forest fire history in southern Switzerland. P-hydroxybenzoic acid was found to be the best organic fire tracer in the study area, revealing the highest correlation with the burned area from fires. Historical records of methylglyoxal, phthalic acid, and dicarboxylic acids adipic acid, sebacic acid, and dodecanedioic acid are comparable with that of anthropogenic emissions of volatile organic compounds (VOCs). The small organic acids, oxalic acid and formic acid, are both highly correlated with calcium, suggesting their records to be affected by changing mineral dust transport to the drilling site.

The Phenazine 2-Hydroxy-Phenazine-1-Carboxylic Acid Promotes Extracellular DNA Release and Has Broad Transcriptomic Consequences in Pseudomonas chlororaphis 30–84

DOE PAGES

Wang, Dongping; Yu, Jun Myoung; Dorosky, Robert J.; ...

2016-01-26

Enhanced production of 2-hydroxy-phenazine-1-carboxylic acid (2-OH-PCA) by the biological control strain Pseudomonas chlororaphis 30–84 derivative 30-84O* was shown previously to promote cell adhesion and alter the three-dimensional structure of surfaceattached biofilms compared to the wild type. The current study demonstrates that production of 2-OH-PCA promotes the release of extracellular DNA, which is correlated with the production of structured biofilm matrix. Moreover, the essential role of the extracellular DNA in maintaining the mass and structure of the 30–84 biofilm matrix is demonstrated. To better understand the role of different phenazines in biofilm matrix production and gene expression, transcriptomic analyses were conductedmore » comparing gene expression patterns of populations of wild type, 30-84O* and a derivative of 30–84 producing only PCA (30-84PCA) to a phenazine defective mutant (30-84ZN) when grown in static cultures. RNA-Seq analyses identified a group of 802 genes that were differentially expressed by the phenazine producing derivatives compared to 30-84ZN, including 240 genes shared by the two 2-OH-PCA producing derivatives, the wild type and 30-84O*. A gene cluster encoding a bacteriophage- derived pyocin and its lysis cassette was upregulated in 2-OH-PCA producing derivatives. A holin encoded in this gene cluster was found to contribute to the release of eDNA in 30–84 biofilm matrices, demonstrating that the influence of 2-OH-PCA on eDNA production is due in part to cell autolysis as a result of pyocin production and release. The results expand the current understanding of the functions different phenazines play in the survival of bacteria in biofilm-forming communities.« less

The Phenazine 2-Hydroxy-Phenazine-1-Carboxylic Acid Promotes Extracellular DNA Release and Has Broad Transcriptomic Consequences in Pseudomonas chlororaphis 30–84

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Dongping; Yu, Jun Myoung; Dorosky, Robert J.

Enhanced production of 2-hydroxy-phenazine-1-carboxylic acid (2-OH-PCA) by the biological control strain Pseudomonas chlororaphis 30–84 derivative 30-84O* was shown previously to promote cell adhesion and alter the three-dimensional structure of surfaceattached biofilms compared to the wild type. The current study demonstrates that production of 2-OH-PCA promotes the release of extracellular DNA, which is correlated with the production of structured biofilm matrix. Moreover, the essential role of the extracellular DNA in maintaining the mass and structure of the 30–84 biofilm matrix is demonstrated. To better understand the role of different phenazines in biofilm matrix production and gene expression, transcriptomic analyses were conductedmore » comparing gene expression patterns of populations of wild type, 30-84O* and a derivative of 30–84 producing only PCA (30-84PCA) to a phenazine defective mutant (30-84ZN) when grown in static cultures. RNA-Seq analyses identified a group of 802 genes that were differentially expressed by the phenazine producing derivatives compared to 30-84ZN, including 240 genes shared by the two 2-OH-PCA producing derivatives, the wild type and 30-84O*. A gene cluster encoding a bacteriophage- derived pyocin and its lysis cassette was upregulated in 2-OH-PCA producing derivatives. A holin encoded in this gene cluster was found to contribute to the release of eDNA in 30–84 biofilm matrices, demonstrating that the influence of 2-OH-PCA on eDNA production is due in part to cell autolysis as a result of pyocin production and release. The results expand the current understanding of the functions different phenazines play in the survival of bacteria in biofilm-forming communities.« less

The Phenazine 2-Hydroxy-Phenazine-1-Carboxylic Acid Promotes Extracellular DNA Release and Has Broad Transcriptomic Consequences in Pseudomonas chlororaphis 30–84

PubMed Central

Wang, Dongping; Yu, Jun Myoung; Dorosky, Robert J.; Pierson, Leland S.; Pierson, Elizabeth A.

2016-01-01

Enhanced production of 2-hydroxy-phenazine-1-carboxylic acid (2-OH-PCA) by the biological control strain Pseudomonas chlororaphis 30–84 derivative 30-84O* was shown previously to promote cell adhesion and alter the three-dimensional structure of surface-attached biofilms compared to the wild type. The current study demonstrates that production of 2-OH-PCA promotes the release of extracellular DNA, which is correlated with the production of structured biofilm matrix. Moreover, the essential role of the extracellular DNA in maintaining the mass and structure of the 30–84 biofilm matrix is demonstrated. To better understand the role of different phenazines in biofilm matrix production and gene expression, transcriptomic analyses were conducted comparing gene expression patterns of populations of wild type, 30-84O* and a derivative of 30–84 producing only PCA (30-84PCA) to a phenazine defective mutant (30-84ZN) when grown in static cultures. RNA-Seq analyses identified a group of 802 genes that were differentially expressed by the phenazine producing derivatives compared to 30-84ZN, including 240 genes shared by the two 2-OH-PCA producing derivatives, the wild type and 30-84O*. A gene cluster encoding a bacteriophage-derived pyocin and its lysis cassette was upregulated in 2-OH-PCA producing derivatives. A holin encoded in this gene cluster was found to contribute to the release of eDNA in 30–84 biofilm matrices, demonstrating that the influence of 2-OH-PCA on eDNA production is due in part to cell autolysis as a result of pyocin production and release. The results expand the current understanding of the functions different phenazines play in the survival of bacteria in biofilm-forming communities. PMID:26812402

Synthesis and Fabrication of Nanocomposite Fibers of Collagen-Cellulose Nanocrystals by Coelectrocompaction.

PubMed

Cudjoe, Elvis; Younesi, Mousa; Cudjoe, Edward; Akkus, Ozan; Rowan, Stuart J

2017-04-10

An electrochemical process has been used to compact cellulose nanocrystals (CNC) and access aligned micron-sized CNC fibers. Placing a current across aqueous solutions of carboxylic acid functionalized CNCs (t-CNC-COOH) or carboxylic acid/primary amine functionalized CNCs (t-CNC-COOH-NH 2 ) creates a pH gradient between the electrodes, which results in the migration and concentration of the CNC fibers at their isoelectric point. By matching the carboxylic acid/amine ratio of CNCs and collagen (ca. 30:70 carboxylic acid:amine ratio), it is possible to coelectrocompact both nanofibers and access aligned nanocomposite fibers. t-CNC-COOH-NH 2 /collagen fibers showed a maximum increase in mechanical properties at 5 wt % of t-CNC-COOH-NH 2 . Compared to collagen/CNC films which have no alignment in the plane of the films, the tensile properties of the aligned fibers show a significant enhancement in the wet mechanical properties (40 MPa vs 230 MPa) for the 5 wt % of t-CNC-COOH-NH 2 /collagen films and fiber, respectively.

Degradation of chitosan hydrogel dispersed in dilute carboxylic acids by solution plasma and evaluation of anticancer activity of degraded products

NASA Astrophysics Data System (ADS)

Chokradjaroen, Chayanaphat; Rujiravanit, Ratana; Theeramunkong, Sewan; Saito, Nagahiro

2018-01-01

Chitosan is a polysaccharide that has been extensively studied in the field of biomedicine, especially its water-soluble degraded products called chitooligosaccharides (COS). In this study, COS were produced by the degradation of chitosan hydrogel dispersed in a dilute solution (i.e., 1.55 mM) of various kinds of carboxylic acids using a non-thermal plasma technology called solution plasma (SP). The degradation rates of chitosan were influenced by the type of carboxylic acids, depending on the interaction between chitosan and each carboxylic acid. After SP treatment, the water-soluble degraded products containing COS could be easily separated from the water-insoluble residue of chitosan hydrogel by centrifugation. The production yields of the COS were mostly higher than 55%. Furthermore, the obtained COS products were evaluated for their inhibitory effect as well as their selectivity against human lung cancer cells (H460) and human lung normal cells (MRC-5).

Biotransformation of fluorophenyl pyridine carboxylic acids by the model fungus Cunninghamella elegans.

PubMed

Palmer-Brown, William; Dunne, Brian; Ortin, Yannick; Fox, Mark A; Sandford, Graham; Murphy, Cormac D

2017-09-01

1. Fluorine plays a key role in the design of new drugs and recent FDA approvals included two fluorinated drugs, tedizolid phosphate and vorapaxar, both of which contain the fluorophenyl pyridyl moiety. 2. To investigate the likely phase-I (oxidative) metabolic fate of this group, various fluorinated phenyl pyridine carboxylic acids were incubated with the fungus Cunninghamella elegans, which is an established model of mammalian drug metabolism. 3.  19 F NMR spectroscopy established the degree of biotransformation, which varied depending on the position of fluorine substitution, and gas chromatography-mass spectrometry (GC-MS) identified alcohols and hydroxylated carboxylic acids as metabolites. The hydroxylated metabolites were further structurally characterised by nuclear magnetic resonance spectroscopy (NMR), which demonstrated that hydroxylation occurred on the 4' position; fluorine in that position blocked the hydroxylation. 4. The fluorophenyl pyridine carboxylic acids were not biotransformed by rat liver microsomes and this was a consequence of inhibitory action, and thus, the fungal model was crucial in obtaining metabolites to establish the mechanism of catabolism.

Accumulation of n-alkanes and carboxylic acids in peat mounds

NASA Astrophysics Data System (ADS)

Gabov, D. N.; Beznosikov, V. A.; Gruzdev, I. V.; Yakovleva, E. V.

2017-10-01

The quantitative and qualitative compositions of n-alkanes and carboxylic acids have been identified, and the features of their vertical stratification in peat mound profiles of the forest-tundra zone of Komi Republic have been revealed. The composition of n-alkanes (structures with C23, C25, C27, C29, and C31) and carboxylic acids (C24, C26, and C28) and their proportions make it possible to determine changes in plant communities of peat mounds with time and can be used as markers for the degree of decomposition of organic matter. In cryogenic horizons, the contents of n-alkanes (mainly C23, C25, and C27) and carboxylic acids (C24, C26, and C28) significantly decrease because of the different botanic composition of cryogenic horizons (grass-woody residues) and seasonally thawing horizons (moss-subshrub residues) and the almost complete stopping of the equilibrium accumulation and transformation of organic compounds in permafrost.

Green and low-cost production of thermally stable and carboxylated cellulose Nanocrystals and nanofibrils using highly recyclable dicarboxylic acids

Treesearch

Huiyang Bian; Liheng Chen; Ruibin Wang; Junyong Zhu

2016-01-01

Here we demonstrate potentially low cost and green productions of high thermally stable and carboxylated cellulose nanocrystals (CNCs) and nanofibrils (CNF) from bleached eucalyptus pulp (BEP) and unbleached mixed hardwood kraft pulp (UMHP) fibers using highly recyclable dicarboxylic solid acids. Typical operating conditions were acid concentrations of 50 - 70 wt% at...

New Drugs for Pretreatment of Organophosphonate Intoxication

DTIC Science & Technology

1990-02-20

amineHydrochlorides 40 1 -Phenylcyclohexane-l-carboxylic Acid 41 Dialkylaminoalkyl 1 -Phenylcycloalkane-l-carboxylate Hydrochlorides 41 3 -Formyl-4,5...cyclopropyl-CH2)- 3 -(Dimethylamino)propyl 1 -Phenylcyclopropane-l-carboxylate Hydrochloride (PRE-150). The recrystallized yield was 18.2 g (53...Arylcycloalkyl)methyl]amines 8 ct,a-Dialkylphenethylamines 9 Dialkylaminoalkyl 1 -Phenylcycloalkane-l-carboxylates 10 3 -Dialkylaminoalkyl-4,5

Partial Hydrothermal Oxidation of High Molecular Weight Unsaturated Carboxylic Acids for Upgrading of Biodiesel Fuel

NASA Astrophysics Data System (ADS)

Kawasaki, K.; Jin, F.; Kishita, A.; Tohji, K.; Enomoto, H.

2007-03-01

With increasing environmental awareness and crude oil price, biodiesel fuel (BDF) is gaining recognition as a renewable fuel which may be used as an alternative diesel fuel without any modification to the engine. The cold flow and viscosity of BDF, however, is a major drawback that limited its use in cold area. In this study, therefore, we investigated that partial oxidation of high molecular weight unsaturated carboxylic acids in subcritical water, which major compositions in BDF, to upgrade biodiesel fuel. Oleic acid, (HOOC(CH2)7CH=CH(CH2)7CH3), was selected as a model compound of high molecular weight unsaturated carboxylic acids. All experiments were performed with a batch reactor made of SUS 316 with an internal volume of 5.7 cm3. Oleic acid was oxidized at 300 °C with oxygen supply varying from 1-10 %. Results showed that a large amount of carboxylic acids and aldehydes having 8-9 carbon atoms were formed. These experimental results suggest that the hydrothermal oxidative cleavage may mainly occur at double bonds and the cleavage of double bonds could improve the cold flow and viscosity of BDF.

4D-Qsar Study of Some Pyrazole Pyridine Carboxylic Acid Derivatives by Electron Conformational-Genetic Algorithm Method.

PubMed

Tuzun, Burak; Yavuz, Sevtap Caglar; Sabanci, Nazmiye; Saripinar, Emin

2018-05-13

In the present work, pharmacophore identification and biological activity prediction for 86 pyrazole pyridine carboxylic acid derivatives were made using the electron conformational genetic algorithm approach which was introduced as a 4D-QSAR analysis by us in recent years. In the light of the data obtained from quantum chemical calculations at HF/6-311 G** level, the electron conformational matrices of congruity (ECMC) were constructed by EMRE software. Comparing the matrices, electron conformational submatrix of activity (ECSA, Pha) was revealed that are common for these compounds within a minimum tolerance. A parameter pool was generated considering the obtained pharmacophore. To determine the theoretical biological activity of molecules and identify the best subset of variables affecting bioactivities, we used the nonlinear least square regression method and genetic algorithm. The results obtained in this study are in good agreement with the experimental data presented in the literature. The model for training and test sets attained by the optimum 12 parameters gave highly satisfactory results with R2training= 0.889, q2=0.839 and SEtraining=0.066, q2ext1 = 0.770, q2ext2 = 0.750, q2ext3=0.824, ccctr = 0.941, ccctest = 0.869 and cccall = 0.927. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Central-to-axial chirality transfer revealed by liquid crystals: a combined experimental and computational approach for the determination of absolute configuration of carboxylic acids with an α chirality centre.

PubMed

Ferrarini, Alberta; Ferroni, Fiammetta; Pieraccini, Silvia; Rosini, Carlo; Superchi, Stefano; Spada, Gian Piero

2011-10-01

The conversion into 6,7-dihydro-5H-dibenz[c,e]azepine (DAZ) N-protected amides is a viable route for the determination of the absolute configuration of chiral 2-substituted carboxylic acids. The biphenyl moiety of DAZ, besides being a probe of chirality for the electronic circular dichroism (ECD) spectroscopy, makes these systems suitable for configuration assignment by exploiting the chirality amplification which occurs in nematic liquid crystals. To assess the reliability of the liquid crystal method in detecting the absolute stereochemistry of chiral amides bound to a biphenyl group, we measured the helical twisting power of a series of DAZ-N-protected amides and compared these data with the results obtained from ECD measurements. We will show that the liquid crystal method, corroborated by HTP predictions, is trustworthy with our biphenyl derivatives, even when ECD spectra are ambiguous for the presence of aryl moieties displaying strong UV absorptions in the same range of the biphenyl chromophore. © 2011 Wiley-Liss, Inc.

Differential metabolism of L-phenylalanine in the formation of aromatic volatiles in melon (Cucumis melo L.) fruit.

PubMed

Gonda, Itay; Davidovich-Rikanati, Rachel; Bar, Einat; Lev, Shery; Jhirad, Pliaa; Meshulam, Yuval; Wissotsky, Guy; Portnoy, Vitaly; Burger, Joseph; Schaffer, Arthur A; Tadmor, Yaakov; Giovannoni, James J; Fei, Zhangjun; Fait, Aaron; Katzir, Nurit; Lewinsohn, Efraim

2018-04-01

Studies on the active pathways and the genes involved in the biosynthesis of L-phenylalanine-derived volatiles in fleshy fruits are sparse. Melon fruit rinds converted stable-isotope labeled L-phe into more than 20 volatiles. Phenylpropanes, phenylpropenes and benzenoids are apparently produced via the well-known phenylpropanoid pathway involving phenylalanine ammonia lyase (PAL) and being (E)-cinnamic acid a key intermediate. Phenethyl derivatives seemed to be derived from L-phe via a separate biosynthetic route not involving (E)-cinnamic acid and PAL. To explore for a biosynthetic route to (E)-cinnamaldehyde in melon rinds, soluble protein cell-free extracts were assayed with (E)-cinnamic acid, CoA, ATP, NADPH and MgSO 4 , producing (E)-cinnamaldehyde in vitro. In this context, we characterized CmCNL, a gene encoding for (E)-cinnamic acid:coenzyme A ligase, inferred to be involved in the biosynthesis of (E)-cinnamaldehyde. Additionally we describe CmBAMT, a SABATH gene family member encoding a benzoic acid:S-adenosyl-L-methionine carboxyl methyltransferase having a role in the accumulation of methyl benzoate. Our approach leads to a more comprehensive understanding of L-phe metabolism into aromatic volatiles in melon fruit. Copyright © 2018 Elsevier Ltd. All rights reserved.

Merging Photoredox and Nickel Catalysis: Decarboxylative Cross-Coupling of Carboxylic Acids with Vinyl Halides

PubMed Central

2015-01-01

Decarboxylative cross-coupling of alkyl carboxylic acids with vinyl halides has been accomplished through the synergistic merger of photoredox and nickel catalysis. This new methodology has been successfully applied to a variety of α-oxy and α-amino acids, as well as simple hydrocarbon-substituted acids. Diverse vinyl iodides and bromides give rise to vinylation products in high efficiency under mild, operationally simple reaction conditions. PMID:25521443

Recovery of carboxylic acids produced during dark fermentation of food waste by adsorption on Amberlite IRA-67 and activated carbon.

PubMed

Yousuf, Ahasa; Bonk, Fabian; Bastidas-Oyanedel, Juan-Rodrigo; Schmidt, Jens Ejbye

2016-10-01

Amberlite IRA-67 and activated carbon were tested as promising candidates for carboxylic acid recovery by adsorption. Dark fermentation was performed without pH control and without addition of external inoculum at 37°C in batch mode. Lactic, acetic and butyric acids, were obtained, after 7days of fermentation. The maximum acid removal, 74%, from the Amberlite IRA-67 and 63% from activated carbon was obtained from clarified fermentation broth using 200gadsorbent/Lbroth at pH 3.3. The pH has significant effect and pH below the carboxylic acids pKa showed to be beneficial for both the adsorbents. The un-controlled pH fermentation creates acidic environment, aiding in adsorption by eliminating use of chemicals for efficient removal. This study proposes simple and easy valorization of waste to valuable chemicals. Copyright © 2016 Elsevier Ltd. All rights reserved.

Chemical Preparation Laboratory IND Candidate Compounds.

DTIC Science & Technology

1986-01-21

filtered. The filtrate was neutralized with hydrochloric acid (3.2 L) and the resulting precipitate was collected by filtration. The product was dried...lit. 242-244-) 1.2.4-Triazole-3-carboxylic acid (4)9: 5-Amino-l,2,4-triazole-3- carboxylic acid (1 Kg, 7.8 mol) was dissolved in hot hydrochloric acid ...300 mL), cooled in an ice bath, and adjusted to pH 1 with con- centrated hydrochloric acid (25 mL). The resulting oil started to crystal- lize and the

Chemical modification and labeling of glutamate residues at the stilbenedisulfonate site of human red blood cell band 3 protein.

PubMed

Jennings, M L; Anderson, M P

1987-02-05

A new method has been developed for the chemical modification and labeling of carboxyl groups in proteins. Carboxyl groups are activated with Woodward's reagent K (N-ethyl-5-phenylisoxazolium 3'-sulfonate), and the adducts are reduced with [3H]BH4. The method has been applied to the anion transport protein of the human red blood cell (band 3). Woodward's reagent K is a reasonably potent inhibitor of band 3-mediated anion transport; a 5-min exposure of intact cells to 2 mM reagent at pH 6.5 produces 80% inhibition of transport. The inhibition is a consequence of modification of residues that can be protected by 4,4'-dinitrostilbene-2,2'-disulfonate. Treatment of intact cells with Woodward's reagent K followed by B3H4 causes extensive labeling of band 3, with minimal labeling of intracellular proteins such as spectrin. Proteolytic digestion of the labeled protein reveals that both the 60- and the 35-kDa chymotryptic fragments are labeled and that the labeling of each is inhibitable by stilbenedisulfonate. If the reduction is performed at neutral pH the major labeled product is the primary alcohol corresponding to the original carboxylic acid. Liquid chromatography of acid hydrolysates of labeled affinity-purified band 3 shows that glutamate but not aspartate residues have been converted into the hydroxyl derivative. This is the first demonstration of the conversion of a glutamate carboxyl group to an alcohol in a protein. The labeling experiments reveal that there are two glutamate residues that are sufficiently close to the stilbenedisulfonate site for their labeling to be blocked by 4,4'-diisothiocyanodihydrostilbene-2,2'-disulfonate and 4,4'-dinitrostilbene-2,2'-disulfonate.

Effect of charged amino acid side chain length on lateral cross-strand interactions between carboxylate- and guanidinium-containing residues in a β-hairpin.

PubMed

Kuo, Hsiou-Ting; Liu, Shing-Lung; Chiu, Wen-Chieh; Fang, Chun-Jen; Chang, Hsien-Chen; Wang, Wei-Ren; Yang, Po-An; Li, Jhe-Hao; Huang, Shing-Jong; Huang, Shou-Ling; Cheng, Richard P

2015-05-01

β-Sheet is one of the major protein secondary structures. Oppositely charged residues are frequently observed across neighboring strands in antiparallel sheets, suggesting the importance of cross-strand ion pairing interactions. The charged amino acids Asp, Glu, Arg, and Lys have different numbers of hydrophobic methylenes linking the charged functionality to the backbone. To investigate the effect of side chain length of guanidinium- and carboxylate-containing residues on lateral cross-strand ion pairing interactions at non-hydrogen-bonded positions, β-hairpin peptides containing Zbb-Agx (Zbb = Asp, Glu, Aad in increasing length; Agx = Agh, Arg, Agb, Agp in decreasing length) sequence patterns were studied by NMR methods. The fraction folded population and folding energy were derived from the chemical shift deviation data. Peptides with high fraction folded populations involved charged residue side chain lengths that supported high strand propensity. Double mutant cycle analysis was used to determine the interaction energy for the potential lateral ion pairs. Minimal interaction was observed between residues with short side chains, most likely due to the diffused positive charge on the guanidinium group, which weakened cross-strand electrostatic interactions with the carboxylate side chain. Only the Aad-Arg/Agh interactions with long side chains clearly exhibited stabilizing energetics, possibly relying on hydrophobics. A survey of a non-redundant protein structure database revealed that the statistical sheet pair propensity followed the trend Asp-Arg < Glu-Arg, implying the need for matching long side chains. This suggested the need for long side chains on both guanidinium-bearing and carboxylate-bearing residues to stabilize the β-hairpin motif.

Isosteric replacements of the carboxylic acid of drug candidate VX-787: Effect of charge on antiviral potency and kinase activity of azaindole-based influenza PB2 inhibitors.

PubMed

Boyd, Michael J; Bandarage, Upul K; Bennett, Hamilton; Byrn, Randal R; Davies, Ioana; Gu, Wenxin; Jacobs, Marc; Ledeboer, Mark W; Ledford, Brian; Leeman, Joshua R; Perola, Emanuele; Wang, Tiansheng; Bennani, Youssef; Clark, Michael P; Charifson, Paul S

2015-05-01

VX-787 is a first in class, orally bioavailable compound that offers unparalleled potential for the treatment of pandemic and seasonal influenza. As a part of our routine SAR exploration, carboxylic acid isosteres of VX-787 were prepared and tested against influenza A. It was found that the negative charge is important for maintaining potency and selectivity relative to kinase targets. Neutral carboxylic acid replacements generally resulted in compounds that were significantly less potent and less selective relative to the charged species. Copyright © 2015 Elsevier Ltd. All rights reserved.

The Conversion of Carboxylic Acids to Ketones: A Repeated Discovery

NASA Astrophysics Data System (ADS)

Nicholson, John W.; Wilson, Alan

2004-09-01

This article describes the history of the reaction converting carboxylic acids to ketones. The reaction has been rediscovered several times, yet has actually been known for centuries. The best known version of the process is the Dakin West reaction (1928), which applies to α-amino acids and also involves the simultaneous conversion of the amine group to amido functionality. Unlike other examples, this particular reaction has attracted a reasonable amount of attention and it appears to be better known than the conversion of simple carboxylic acids to ketones. However, this reaction was described as long ago as 1612, when Beguin published an account of it in his book, Tyrocinium Chymicum . Since then, many chemists have rediscovered the reaction, apparently independently. One of the earliest modern accounts was by W. H. Perkin, Sr., in 1886, who made various simple ketones by refluxing the appropriate carboxylic acids with base. However, this work has been largely ignored, including by his son, W. H. Perkin, Jr., who used a more complicated base-catalyzed ketonization to prepare small ring compounds in the early years of the 20th century. Other articles detailing the application of ketonization to organic acids are discussed, including our own work, which employed the process to crosslink carboxylated polymers for possible technical application in coatings. Despite its relative obscurity, the reaction was used by Woodward et al. in the total synthesis of strychnine, reported in 1963, and this is discussed in detail at the end of the article. See Featured Molecules .

Structure determination of metabolites isolated from urine and bile after administration of AY4166, a novel D-phenylalanine-derivative hypoglycemic agent.

PubMed

Takesada, H; Matsuda, K; Ohtake, R; Mihara, R; Ono, I; Tanaka, K; Naito, M; Yatagai, M; Suzuki, E

1996-10-01

Molecular structures of 10 metabolites, which were isolated from urine (M1-M8) or bile (M9 and M10) after administration of AY4166 (N-(trans-4-isopropylcyclohexanecarbonyl)-D-phenylalanine), a novel amino acid derivative with hypoglycemic activity, have been elucidated by mass spectrometry and nuclear magnetic resonance. Four of these (M1, M2, M3 and M8) were determined to be hydroxyl derivatives of AY4166, two (M9 and M10) were carboxylate derivatives via oxidization of M2 and M3, three (M4, M5 and M6) were glucronic acid conjugates and the other (M7) was a dehydro derivative. The estimated structures for M1, M2, M3, M7, M8, M9 and M10 were confirmed by the coincidence of the retention time of HPLC, MS and 1H NMR spectra between the isolated metabolites and authentic synthesized substances. For three glucronic acid conjugates, M4, M5 and M6, structural confirmation was performed by a selective enzymatic digestion with beta-glucronidase. M1 and M2/3 were about 5-6 and 3 times less potent than AY4166, respectively, and M7 was almost as potent as AY4166.

Improvement of ruthenium based decarboxylation of carboxylic acids

USDA-ARS?s Scientific Manuscript database

The removal of oxygen atoms from biobased carboxylic acids is an attractive route to provide the drop in replacement feedstocks that industry needs to continue to provide high performance products. Through the use of ruthenium catalysis, an efficient method where this process can be accomplished on ...

An enantioselective route to alpha-methyl carboxylic acids via metal and enzyme catalysis.

PubMed

Norinder, Jakob; Bogár, Krisztián; Kanupp, Lisa; Bäckvall, Jan-E

2007-11-22

Dynamic kinetic resolution of allylic alcohols to allylic acetates followed by copper-catalyzed allylic substitution gave alkenes in high yields and high optical purity. Subsequent oxidative C-C double bond cleavage afforded pharmaceutically important alpha-methyl substituted carboxylic acids in high ee.

Effect of chirality on cellular uptake, imaging and photodynamic therapy of photosensitizers derived from chlorophyll-a.

PubMed

Srivatsan, Avinash; Pera, Paula; Joshi, Penny; Wang, Yanfang; Missert, Joseph R; Tracy, Erin C; Tabaczynski, Walter A; Yao, Rutao; Sajjad, Munawwar; Baumann, Heinz; Pandey, Ravindra K

2015-07-01

We have previously shown that the (124)I-analog of methyl 3-(1'-m-iodobenzyloxy) ethyl-3-devinyl-pyropheophorbide-a derived as racemic mixture from chlorophyll-a can be used for PET (positron emission tomography)-imaging in animal tumor models. On the other hand, as a non-radioactive analog, it showed excellent fluorescence and photodynamic therapy (PDT) efficacy. Thus, a single agent in a mixture of radioactive ((124)I-) and non-radioactive ((127)I) material can be used for both dual-imaging and PDT of cancer. Before advancing to Phase I human clinical trials, we evaluated the activity of the individual isomers as well as the impact of a chiral center at position-3(1) in directing in vitro/in vivo cellular uptake, intracellular localization, epithelial tumor cell-specific retention, fluorescence/PET imaging, and photosensitizing ability. The results indicate that both isomers (racemates), either as methyl ester or carboxylic acid, were equally effective. However, the methyl ester analogs, due to subcellular deposition into vesicular structures, were preferentially retained. All derivatives containing carboxylic acid at the position-17(2) were noted to be substrate for the ABCG2 (a member of the ATP binding cassette transporters) protein explaining their low retention in lung tumor cells expressing this transporter. The compounds in which the chirality at position-3 has been substituted by a non-chiral functionality showed reduced cellular uptake, retention and lower PDT efficacy in mice bearing murine Colon26 tumors. Copyright © 2015 Elsevier Ltd. All rights reserved.

Role of the ribose-specific marker furfuryl-amine in the formation of aroma active 1-(furan-2-ylmethyl)-1H-pyrrole (or furfuryl-pyrrole) derivatives.

PubMed

Nikolov, Plamen Y; Yaylayan, Varoujan A

2012-10-10

Furfuryl-pyrroles possess a diverse range of organoleptic properties described as roasted, chocolaty, green, horseradish-like, and mushroom-like and are detected in various foods such as coffee, chocolate, popcorn, and roasted chicken. Although their origin in food was attributed to furfuryl-amine, the latter has not been detected so far in Maillard model systems or in foods. In this study, furfuryl-amine was shown to be formed specifically from ribose through nitrogen atom transfer from the α-amino group of any amino acid. Such a transfer can be achieved through decarboxylation of the Schiff base adduct and isomerization followed by hydrolysis. Through the use of (15)Nα-lysine it was revealed that only the (15)Nα nitrogen atom was incorporated into its structure, indicating a specific role for the carboxylate moiety in the mechanism of its formation. Furthermore, isotope labeling studies have indicated that furfuryl-pyrrole derivatives can be formed by the interaction of 2 mol of furfuryl-amine with 3-deoxyribosone followed by dehydration and cyclization to form 1-(furan-2-yl)-N-{[1-(furan-2-ylmethyl)-1H-pyrrol-2-yl]methylidene}methanamine. After hydrolysis, this intermediate can generate furfuryl-formyl-pyrrole, furfuryl-pyrrole carboxylic acid, and furfuryl-pyrrole. In this study, the furfuryl-amine derivatives were also detected in different coffee beans after pyrolysis and analysis by GC-MS. The potential of these compounds to form in aqueous model systems at a temperature of 120 °C was also demonstrated.

Inhibition of veratridine-induced delayed inactivation of the voltage-sensitive sodium channel by synthetic analogs of crambescin B.

PubMed

Tsukamoto, Tadaaki; Chiba, Yukie; Nakazaki, Atsuo; Ishikawa, Yuki; Nakane, Yoshiki; Cho, Yuko; Yotsu-Yamashita, Mari; Nishikawa, Toshio; Wakamori, Minoru; Konoki, Keiichi

2017-03-01

Crambescin B carboxylic acid, a synthetic analog of crambescin B, was recently found to inhibit the voltage-sensitive sodium channels (VSSC) in a cell-based assay using neuroblastoma Neuro 2A cells. In the present study, whole-cell patch-clamp recordings were conducted with three heterologously expressed VSSC subtypes, Na v 1.2, Na v 1.6 and Na v 1.7, in a human embryonic kidney cell line HEK293T to further characterize the inhibition of VSSC by crambescin B carboxylic acid. Contrary to the previous observation, crambescin B carboxylic acid did not inhibit peak current evoked by depolarization from the holding potential of -100mV to the test potential of -10mV in the absence or presence of veratridine (VTD). In the presence of VTD, however, crambescin B carboxylic acid diminished VTD-induced sustained and tail currents through the three VSSC subtypes in a dose-dependent manner, whereas TTX inhibited both the peak current and the VTD-induced sustained and tail currents through all subtypes of VSSC tested. We thus concluded that crambescin B carboxylic acid does not block VSSC in a similar manner to TTX but modulate the action of VTD, thereby causing an apparent block of VSSC in the cell-based assay. Copyright © 2017 Elsevier Ltd. All rights reserved.

Adsorption of acetanilide herbicides on soil and its components. II. Adsorption and catalytic hydrolysis of diethatyl-ethyl on saturated Na(+)-, K(+)-, Ca(2+)-, and Mg(2+)-montmorillonite.

PubMed

Liu, W P; Fang, Z; Liu, H J; Yang, W C

2001-04-01

Adsorption and catalytic hydrolysis of the herbicide diethatyl-ethyl [N-chloroacetyl-N-(2,6-diethylphenyl)glycine ethyl ester] on homoionic Na(+)-, K(+)-, Ca(2+)-, and Mg(2+)-montmorillonite clays were investigated in water solution. The Freundlich adsorption coefficient, Ki, got from isotherms on clay followed the order of Na+ approximately K+ > Mg2+ approximately Ca2+. Analysis of FT-IR spectra of diethatyl-ethyl adsorbed on clay suggests probable bonding at the carboxyl and amide carbonyl groups of the herbicide. The rate of herbicide hydrolysis in homoionic clay suspensions followed the same order as that for adsorption, indicating that adsorption may have preceded and thus caused hydrolysis. Preliminary product identification showed that hydrolysis occurred via nucleophilic substitution at the carboxyl carbon, causing the cleavage of the ester bond and formation of diethatyl and its dechlorinated derivative, and at the amide carbon, yielding an ethyl ester derivative and its acid. These pathways also suggest that hydrolysis of diethatyl-ethyl was catalyzed by adsorption on the clay surface.

Synthesis and structural and conformational study of some esters derived from 8-β-hydroxy-3-phenethyl-3- azabicyclico [3.2.11] octan-8-α-carboxylic acid

NASA Astrophysics Data System (ADS)

Diez, M.; Izquierdo, M. L.; Arias, M. S.; Galvez, E.; Matesanz, E.; Martinez-Ripoll, M.

1991-09-01

A series of 8-β-hydroxy-8-α-alkoxycarbonyl- N-phenethyl-3-azabicyclo [3.2.1.]octane derivatives have been synthesized and studied by IR, 1H and 13C NMR spectroscopy, and the crystal structure of ethyl-8-β-hydroxy-3-phenethyl-3-azabicyclo [3.2.1] octan-8-α-carboxylate ( Va) has been determined by X-ray diffraction. In deuterochloroform and deuterobenzene the cyclopentane and piperidine rings of the title compounds show an envelope conformation flattened at C8 and a distorted chair conformation puckered at C8 and flattened at N3, respectively, with the N-substituent in an equatorial position. These results are in close agreement with that found for compound Va in the crystalline state. By comparing the NMR and X-ray parameters of the title compounds with those of the corresponding 8-α-hydroxy-8β-alkoxycarbonyl- N-phenethyl-3- azabicyclo [3.2.1] octane epimers and 3-phenethyl-3-azabicyclo [3.2.1] octan-8-α-(andβ)ol, several stereoelectronic effects have been deduced.

Chemical Conversions of Biomass-Derived Platform Chemicals over Copper-Silica Nanocomposite Catalysts.

PubMed

Upare, Pravin P; Hwang, Young Kyu; Lee, Jong-Min; Hwang, Dong Won; Chang, Jong-San

2015-07-20

Biomass and biomass-derived carbohydrates have a high extent of functionality, unlike petroleum, which has limited functionality. In biorefinery applications, the development of methods to control the extent of functionality in final products intended for use as fuels and chemicals is a challenge. In the chemical industry, heterogeneous catalysis is an important tool for the defunctionalization of functionalized feedstocks and biomass-derived platform chemicals to produce value-added chemicals. Herein, we review the recent progress in this field, mainly of vapor phase chemical conversion of biomass-derived C4 -C6 carboxylic acids and esters using copper-silica nanocomposite catalysts. We also demonstrate that these nanocomposite catalysts very efficiently convert biomass-derived platform chemicals into cyclic compounds, such as lactones and hydrofurans, with high selectivities and yields. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Metabolic engineering of tomato fruit organic acid content guided by biochemical analysis of an introgression line.

PubMed

Morgan, Megan J; Osorio, Sonia; Gehl, Bernadette; Baxter, Charles J; Kruger, Nicholas J; Ratcliffe, R George; Fernie, Alisdair R; Sweetlove, Lee J

2013-01-01

Organic acid content is regarded as one of the most important quality traits of fresh tomato (Solanum lycopersicum). However, the complexity of carboxylic acid metabolism and storage means that it is difficult to predict the best way to engineer altered carboxylic acid levels. Here, we used a biochemical analysis of a tomato introgression line with increased levels of fruit citrate and malate at breaker stage to identify a metabolic engineering target that was subsequently tested in transgenic plants. Increased carboxylic acid levels in introgression line 2-5 were not accompanied by changes in the pattern of carbohydrate oxidation by pericarp discs or the catalytic capacity of tricarboxylic acid cycle enzymes measured in isolated mitochondria. However, there was a significant decrease in the maximum catalytic activity of aconitase in total tissue extracts, suggesting that a cytosolic isoform of aconitase was affected. To test the role of cytosolic aconitase in controlling fruit citrate levels, we analyzed fruit of transgenic lines expressing an antisense construct against SlAco3b, one of the two tomato genes encoding aconitase. A green fluorescent protein fusion of SlAco3b was dual targeted to cytosol and mitochondria, while the other aconitase, SlAco3a, was exclusively mitochondrial when transiently expressed in tobacco (Nicotiana tabacum) leaves. Both aconitase transcripts were decreased in fruit from transgenic lines, and aconitase activity was reduced by about 30% in the transgenic lines. Other measured enzymes of carboxylic acid metabolism were not significantly altered. Both citrate and malate levels were increased in ripe fruit of the transgenic plants, and as a consequence, total carboxylic acid content was increased by 50% at maturity.

Metabolic Engineering of Tomato Fruit Organic Acid Content Guided by Biochemical Analysis of an Introgression Line1[W][OA

PubMed Central

Morgan, Megan J.; Osorio, Sonia; Gehl, Bernadette; Baxter, Charles J.; Kruger, Nicholas J.; Ratcliffe, R. George; Fernie, Alisdair R.; Sweetlove, Lee J.

2013-01-01

Organic acid content is regarded as one of the most important quality traits of fresh tomato (Solanum lycopersicum). However, the complexity of carboxylic acid metabolism and storage means that it is difficult to predict the best way to engineer altered carboxylic acid levels. Here, we used a biochemical analysis of a tomato introgression line with increased levels of fruit citrate and malate at breaker stage to identify a metabolic engineering target that was subsequently tested in transgenic plants. Increased carboxylic acid levels in introgression line 2-5 were not accompanied by changes in the pattern of carbohydrate oxidation by pericarp discs or the catalytic capacity of tricarboxylic acid cycle enzymes measured in isolated mitochondria. However, there was a significant decrease in the maximum catalytic activity of aconitase in total tissue extracts, suggesting that a cytosolic isoform of aconitase was affected. To test the role of cytosolic aconitase in controlling fruit citrate levels, we analyzed fruit of transgenic lines expressing an antisense construct against SlAco3b, one of the two tomato genes encoding aconitase. A green fluorescent protein fusion of SlAco3b was dual targeted to cytosol and mitochondria, while the other aconitase, SlAco3a, was exclusively mitochondrial when transiently expressed in tobacco (Nicotiana tabacum) leaves. Both aconitase transcripts were decreased in fruit from transgenic lines, and aconitase activity was reduced by about 30% in the transgenic lines. Other measured enzymes of carboxylic acid metabolism were not significantly altered. Both citrate and malate levels were increased in ripe fruit of the transgenic plants, and as a consequence, total carboxylic acid content was increased by 50% at maturity. PMID:23166354

Nano-graphene oxide carboxylation for efficient bioconjugation applications: a quantitative optimization approach

NASA Astrophysics Data System (ADS)

Imani, Rana; Emami, Shahriar Hojjati; Faghihi, Shahab

2015-02-01

A method for carboxylation of graphene oxide (GO) with chloroacetic acid that precisely optimizes and controls the efficacy of the process for bioconjugation applications is proposed. Quantification of COOH groups on nano-graphene oxide sheets (NGOS) is performed by novel colorimetric methylene blue (MB) assay. The GO is synthesized and carboxylated by chloroacetic acid treatment under strong basic condition. The size and morphology of the as-prepared NGOS are characterized by scanning electron microscopy, transmission electron microscopy (TEM), and atomic force microscopy (AFM). The effect of acid to base molar ratio on the physical, chemical, and morphological properties of NGOS is analyzed by Fourier-transformed infrared spectrometry (FTIR), UV-Vis spectroscopy, X-ray diffraction (XRD), AFM, and zeta potential. For evaluation of bioconjugation efficacy, the synthesized nano-carriers with different carboxylation ratios are functionalized by octaarginine peptide sequence (R8) as a biomolecule model containing amine groups. The quantification of attached R8 peptides to graphene nano-sheets' surface is performed with a colorimetric-based assay which includes the application of 2,4,6-Trinitrobenzene sulfonic acid (TNBS). The results show that the thickness and lateral size of nano-sheets are dramatically decreased to 0.8 nm and 50-100 nm after carboxylation process, respectively. X-ray analysis shows the nano-sheets interlaying space is affected by the alteration of chloroacetic acid to base ratio. The MB assay reveals that the COOH groups on the surface of NGOS are maximized at the acid to base ratio of 2 which is confirmed by FTIR, XRD, and zeta potential. The TNBS assay also shows that bioconjugation of the optimized carboxylated NGOS sample with octaarginine peptide is 2.5 times more efficient compared to bare NGOS. The present work provides evidence that treatment of GO by chloroacetic acid under an optimized condition would create a functionalized high surface area nano-substrate which can be used for subsequent efficient bioconjugation applications.

A 13C{31P} REDOR NMR Investigation of the Role of Glutamic Acid Residues in Statherin-Hydroxyapatite Recognition

PubMed Central

Ndao, Moise; Ash, Jason T.; Breen, Nicholas F.; Goobes, Gil; Stayton, Patrick S.; Drobny, Gary P.

2011-01-01

The side chain carboxyl groups of acidic proteins found in the extra-cellular matrix (ECM) of mineralized tissues play a key role in promoting or inhibiting the growth of minerals such as hydroxyapatite (HAP), the principal mineral component of bone and teeth. Among the acidic proteins found in the saliva is statherin, a 43-residue tyrosine-rich peptide that is a potent lubricant in the salivary pellicle and an inhibitor of both HAP crystal nucleation and growth. Three acidic amino acids – D1, E4, and E5 – are located in the N-terminal 15 amino acid segment, with a fourth amino acid, E26, located outside the N-terminus. We have utilized 13C{31P} REDOR NMR to analyze the role played by acidic amino acids in the binding mechanism of statherin to the HAP surface by measuring the distance between the δ-carboxyl 13C spins of the three glutamic acid side chains of statherin (residues E4, E5, E26) and 31P spins of the phosphate groups at the HAP surface. 13C{31P} REDOR studies of glutamic-5-13C acid incorporated at positions E4 and E26 indicate a 13C–31P distance of more than 6.5 Å between the side chain carboxyl 13C spin of E4 and the closest 31P in the HAP surface. In contrast, the carboxyl 13C spin at E5 has a much shorter 13C–31P internuclear distance of 4.25±0.09 Å, indicating that the carboxyl group of this side chain interacts directly with the surface. 13C T1ρ and slow-spinning MAS studies indicate that the motions of the side chains of E4 and E5 are more restricted than that of E26. Together, these results provide further insight into the molecular interactions of statherin with HAP surfaces. PMID:19678690

Antibacterial, antibiofilm and antioxidant screening of copper(II)-complexes with some S-alkyl derivatives of thiosalicylic acid. Crystal structure of the binuclear copper(II)-complex with S-propyl derivative of thiosalicylic acid

NASA Astrophysics Data System (ADS)

Bukonjić, Andriana M.; Tomović, Dušan Lj.; Nikolić, Miloš V.; Mijajlović, Marina Ž.; Jevtić, Verica V.; Ratković, Zoran R.; Novaković, Slađana B.; Bogdanović, Goran A.; Radojević, Ivana D.; Maksimović, Jovana Z.; Vasić, Sava M.; Čomić, Ljiljana R.; Trifunović, Srećko R.; Radić, Gordana P.

2017-01-01

The spectroscopically predicted structure of the obtained copper(II)-complex with S-propyl derivative of thiosalicylic acid was confirmed by X-ray structural study. The binuclear copper(II)-complex with S-propyl derivative of thiosalicylic acid crystallized in two polymorphic forms with main structural difference in the orientation of phenyl rings relative to corresponding carboxylate groups. The antibacterial activity was tested determining the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) by using microdilution method. The influence on bacterial biofilm formation was determined by tissue culture plate method. In general, the copper(II)-complexes manifested a selective and moderate activity. The most sensitive bacteria to the effects of Cu(II)-complexes was a clinical isolate of Pseudomonas aeruginosa. For this bacteria MIC and biofilm inhibitory concentration (BIC) values for all tested complexes were in the range or better than the positive control, doxycycline. Also, for the established biofilm of clinical isolate Staphylococcus aureus, BIC values for the copper(II)-complex with S-ethyl derivative of thiosalicylic acid,[Cu2(S-et-thiosal)4(H2O)2] (C3) and copper(II)-complex with S-butyl derivative of thiosalicylic acid, [Cu2(S-bu-thiosal)4(H2O)2] (C5) were in range or better than the positive control. All the complexes acted better against Gram-positive bacteria (Staphylococcus aureus and Staphylococcus aureus ATCC 25923) than Gram-negative bacteria (Proteus mirabilis ATCC 12453, Pseudomonas aeruginosa, and P. aeruginosa ATCC 27855). The complexes showed weak antioxidative properties tested by two methods (1,1-diphenyl-2-picrylhydrazyl (DPPH) and reducing power assay).

New Chemistry with Old Functional Groups: On the Reaction of Isonitriles with Carboxylic Acids - A Route to Various Amide Types

PubMed Central

Li, Xuechen; Danishefsky, Samuel J.

2008-01-01

Thermolysis of isonitriles with carboxylic acids provides, in one step, N-formyl imides (see, for example 8 + 19 → 21). The resultant N-formyl group can be converted to N-H, NCH2OH or NCH3. This chemistry allows for a new route for synthesizing β-N (asparagine) linked glycosyl amino acids. PMID:18370392

Consolidated bioprocessing of microalgal biomass to carboxylates by a mixed culture of cow rumen bacteria using anaerobic sequencing batch reactor (ASBR).

PubMed

Zhao, Baisuo; Liu, Jie; Frear, Craig; Holtzapple, Mark; Chen, Shulin

2016-12-01

This study employed mixed-culture consolidated bioprocessing (CBP) to digest microalgal biomass in an anaerobic sequencing batch reactor (ASBR). The primary objectives are to evaluate the impact of hydraulic residence time (HRT) on the productivity of carboxylic acids and to characterize the bacterial community. HRT affects the production rate and patterns of carboxylic acids. For the 5-L laboratory-scale fermentation, a 12-day HRT was selected because it offered the highest productivity of carboxylic acids and it synthesized longer chains. The variability of the bacterial community increased with longer HRT (R 2 =0.85). In the 5-L laboratory-scale fermentor, the most common phyla were Firmicutes (58.3%), Bacteroidetes (27.4%), and Proteobacteria (11.9%). The dominant bacterial classes were Clostridia (29.8%), Bacteroidia (27.4%), Tissierella (26.2%), and Betaproteobacteria (8.9%). Copyright © 2016 Elsevier Ltd. All rights reserved.

ESTIMATION OF HYDROLYSIS RATE CONSTANTS OF CARBOXYLIC ACID ESTER AND PHOSPHATE ESTER COMPOUNDS IN AQUEOUS SYSTEMS FROM MOLECULAR STRUCTURE BY SPARC

EPA Science Inventory

SPARC (SPARC Performs Automated Reasoning in Chemistry) chemical reactivity models were extended to calculate hydrolysis rate constants for carboxylic acid ester and phosphate ester compounds in aqueous non- aqueous and systems strictly from molecular structure. The energy diffe...

EFFECTS OF CARBOXYLIC ACIDS ON LIQUID-PHASE ADSORPTION OF ETHANOL AND WATER BY HIGH-SILICA ZSM-5

EPA Science Inventory

Adsorption isotherms were measured for each compound adsorbed on commercially available ZSM-5 (Si/Al = 140) powder from binary and ternary liquid mixtures of ethanol, carboxylic acids, and water at room temperature. The amounts adsorbed were measured using a recently developed t...

10 CFR 26.185 - Determining a fitness-for-duty policy violation.

Code of Federal Regulations, 2012 CFR

2012-01-01

... was marijuana and the confirmatory assay for delta-9-tetrahydrocannabinol-9-carboxylic acid yields a positive result, the MRO shall determine whether the confirmatory test result indicates further marijuana... delta-9-tetrahydrocannabinol-9-carboxylic acid that would be expected if no further marijuana use had...

10 CFR 26.185 - Determining a fitness-for-duty policy violation.

Code of Federal Regulations, 2013 CFR

2013-01-01

... was marijuana and the confirmatory assay for delta-9-tetrahydrocannabinol-9-carboxylic acid yields a positive result, the MRO shall determine whether the confirmatory test result indicates further marijuana... delta-9-tetrahydrocannabinol-9-carboxylic acid that would be expected if no further marijuana use had...

10 CFR 26.185 - Determining a fitness-for-duty policy violation.

Code of Federal Regulations, 2014 CFR

2014-01-01

... was marijuana and the confirmatory assay for delta-9-tetrahydrocannabinol-9-carboxylic acid yields a positive result, the MRO shall determine whether the confirmatory test result indicates further marijuana... delta-9-tetrahydrocannabinol-9-carboxylic acid that would be expected if no further marijuana use had...

Organotin(IV) carboxylates based on 2-(1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)acetic acid: Syntheses, crystal structures, luminescent properties and antitumor activities

NASA Astrophysics Data System (ADS)

Xiao, Xiao; Liang, Jingwen; Xie, Jingyi; Liu, Xin; Zhu, Dongsheng; Dong, Yuan

2017-10-01

Organotin carboxylates based on an amide carboxylic acid 2-(1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)acetic acid (HL): [(Bn2Sn)2O2L]2·2C6H6 (1) (Bn = benzyl group) and (Ph2Sn)(L)2 (2) were synthesized and characterized by elemental analysis, IR, 1H, 13C, 119Sn NMR spectroscopy and X-ray crystallography diffraction analysis. Complex 1 is dimeric carboxylate tetraorganodistannoxane and show a "ladder-like" molecular structure. Complex 2 is a dialkyltin carboxylate monomer possessing crystallographically imposed two-fold symmetry. Ligand in 1 and 2 adopts unidentate and bidentate coordination respectively. Both 1 and 2 form 1D, 2D and 3D supramolecular organizations in the solid state mediated through Csbnd H⋯O and π⋯π interactions which are discussed in detail. The luminescent properties and preliminary antitumor activities about this series of complexes were also studied.

Biosynthesis of Germacrene A Carboxylic Acid in Chicory Roots. Demonstration of a Cytochrome P450 (+)-Germacrene A Hydroxylase and NADP+-Dependent Sesquiterpenoid Dehydrogenase(s) Involved in Sesquiterpene Lactone Biosynthesis

PubMed Central

de Kraker, Jan-Willem; Franssen, Maurice C. R.; Dalm, Marcella C. F.; de Groot, Aede; Bouwmeester, Harro J.

2001-01-01

Sprouts of chicory (Cichorium intybus), a vegetable grown in the dark, have a slightly bitter taste associated with the presence of guaianolides, eudesmanolides, and germacranolides. The committed step in the biosynthesis of these compounds is catalyzed by a (+)-germacrene A synthase. Formation of the lactone ring is the postulated next step in biosynthesis of the germacrene-derived sesquiterpene lactones. The present study confirms this hypothesis by isolation of enzyme activities from chicory roots that introduce a carboxylic acid function in the germacrene A isopropenyl side chain, which is necessary for lactone ring formation. (+)-Germacrene A is hydroxylated to germacra-1(10),4,11(13)-trien-12-ol by a cytochrome P450 enzyme, and is subsequently oxidized to germacra-1(10),4,11(13)-trien-12-oic acid by NADP+-dependent dehydrogenase(s). Both oxidized germacrenes were detected as their Cope-rearrangement products elema-1,3,11(13)-trien-12-ol and elema-1,3,11(13)-trien-12-oic acid, respectively. The cyclization products of germacra-1(10),4,11(13)-trien-12-ol, i.e. costol, were also observed. The (+)-germacrene A hydroxylase is inhibited by carbon monoxide (blue-light reversible), has an optimum pH at 8.0, and hydroxylates β-elemene with a modest degree of enantioselectivity. PMID:11299372

Ionotropic Receptors Mediate Drosophila Oviposition Preference through Sour Gustatory Receptor Neurons.

PubMed

Chen, Yan; Amrein, Hubert

2017-09-25

Carboxylic acids are present in many foods, being especially abundant in fruits. Yet, relatively little is known about how acids are detected by gustatory systems and whether they have a potential role in nutrition or provide other health benefits. Here we identify sour gustatory receptor neurons (GRNs) in tarsal taste sensilla of Drosophila melanogaster. We find that most tarsal sensilla harbor a sour GRN that is specifically activated by carboxylic and mineral acids but does not respond to sweet- and bitter-tasting chemicals or salt. One pair of taste sensilla features two GRNs that respond only to a subset of carboxylic acids and high concentrations of salt. All sour GRNs prominently express two Ionotropic Receptor (IR) genes, IR76b and IR25a, and we show that both these genes are necessary for the detection of acids. Furthermore, we establish that IR25a and IR76b are essential in sour GRNs of females for oviposition preference on acid-containing food. Our investigations reveal that acids activate a unique set of taste cells largely dedicated to sour taste, and they indicate that both pH/proton concentration and the structure of carboxylic acids contribute to sour GRN activation. Together, our studies provide new insights into the cellular and molecular basis of sour taste. Copyright © 2017 Elsevier Ltd. All rights reserved.

Facile regio- and stereoselective hydrometalation of alkynes with a combination of carboxylic acids and group 10 transition metal complexes: selective hydrogenation of alkynes with formic acid.

PubMed

Shen, Ruwei; Chen, Tieqiao; Zhao, Yalei; Qiu, Renhua; Zhou, Yongbo; Yin, Shuangfeng; Wang, Xiangbo; Goto, Midori; Han, Li-Biao

2011-10-26

A facile, highly stereo- and regioselective hydrometalation of alkynes generating alkenylmetal complex is disclosed for the first time from a reaction of alkyne, carboxylic acid, and a zerovalent group 10 transition metal complex M(PEt(3))(4) (M = Ni, Pd, Pt). A mechanistic study showed that the hydrometalation does not proceed via the reaction of alkyne with a hydridometal generated by the protonation of a carboxylic acid with Pt(PEt(3))(4), but proceeds via a reaction of an alkyne coordinate metal complex with the acid. This finding clarifies the long proposed reaction mechanism that operates via the generation of an alkenylpalladium intermediate and subsequent transformation of this complex in a variety of reactions catalyzed by a combination of Brϕnsted acid and Pd(0) complex. This finding also leads to the disclosure of an unprecedented reduction of alkynes with formic acid that can selectively produce cis-, trans-alkenes and alkanes by slightly tuning the conditions.

Structure-Activity Relationship Study of Ionotropic Glutamate Receptor Antagonist (2S,3R)-3-(3-Carboxyphenyl)pyrrolidine-2-carboxylic Acid.

PubMed

Krogsgaard-Larsen, Niels; Storgaard, Morten; Møller, Charlotte; Demmer, Charles S; Hansen, Jeanette; Han, Liwei; Monrad, Rune N; Nielsen, Birgitte; Tapken, Daniel; Pickering, Darryl S; Kastrup, Jette S; Frydenvang, Karla; Bunch, Lennart

2015-08-13

Herein we describe the first structure-activity relationship study of the broad-range iGluR antagonist (2S,3R)-3-(3-carboxyphenyl)pyrrolidine-2-carboxylic acid (1) by exploring the pharmacological effect of substituents in the 4, 4', or 5' positions and the bioisosteric substitution of the distal carboxylic acid for a phosphonic acid moiety. Of particular interest is a hydroxyl group in the 4' position 2a which induced a preference in binding affinity for homomeric GluK3 over GluK1 (Ki = 0.87 and 4.8 μM, respectively). Two X-ray structures of ligand binding domains were obtained: 2e in GluA2-LBD and 2f in GluK1-LBD, both at 1.9 Å resolution. Compound 2e induces a D1-D2 domain opening in GluA2-LBD of 17.3-18.8° and 2f a domain opening in GluK1-LBD of 17.0-17.5° relative to the structures with glutamate. The pyrrolidine-2-carboxylate moiety of 2e and 2f shows a similar binding mode as kainate. The 3-carboxyphenyl ring of 2e and 2f forms contacts comparable to those of the distal carboxylate in kainate.

Tumor microenvironment derived exosomes pleiotropically modulate cancer cell metabolism.

PubMed

Zhao, Hongyun; Yang, Lifeng; Baddour, Joelle; Achreja, Abhinav; Bernard, Vincent; Moss, Tyler; Marini, Juan C; Tudawe, Thavisha; Seviour, Elena G; San Lucas, F Anthony; Alvarez, Hector; Gupta, Sonal; Maiti, Sourindra N; Cooper, Laurence; Peehl, Donna; Ram, Prahlad T; Maitra, Anirban; Nagrath, Deepak

2016-02-27

Cancer-associated fibroblasts (CAFs) are a major cellular component of tumor microenvironment in most solid cancers. Altered cellular metabolism is a hallmark of cancer, and much of the published literature has focused on neoplastic cell-autonomous processes for these adaptations. We demonstrate that exosomes secreted by patient-derived CAFs can strikingly reprogram the metabolic machinery following their uptake by cancer cells. We find that CAF-derived exosomes (CDEs) inhibit mitochondrial oxidative phosphorylation, thereby increasing glycolysis and glutamine-dependent reductive carboxylation in cancer cells. Through 13C-labeled isotope labeling experiments we elucidate that exosomes supply amino acids to nutrient-deprived cancer cells in a mechanism similar to macropinocytosis, albeit without the previously described dependence on oncogenic-Kras signaling. Using intra-exosomal metabolomics, we provide compelling evidence that CDEs contain intact metabolites, including amino acids, lipids, and TCA-cycle intermediates that are avidly utilized by cancer cells for central carbon metabolism and promoting tumor growth under nutrient deprivation or nutrient stressed conditions.

Tumor microenvironment derived exosomes pleiotropically modulate cancer cell metabolism

PubMed Central

Zhao, Hongyun; Yang, Lifeng; Baddour, Joelle; Achreja, Abhinav; Bernard, Vincent; Moss, Tyler; Marini, Juan C; Tudawe, Thavisha; Seviour, Elena G; San Lucas, F Anthony; Alvarez, Hector; Gupta, Sonal; Maiti, Sourindra N; Cooper, Laurence; Peehl, Donna; Ram, Prahlad T; Maitra, Anirban; Nagrath, Deepak

2016-01-01

Cancer-associated fibroblasts (CAFs) are a major cellular component of tumor microenvironment in most solid cancers. Altered cellular metabolism is a hallmark of cancer, and much of the published literature has focused on neoplastic cell-autonomous processes for these adaptations. We demonstrate that exosomes secreted by patient-derived CAFs can strikingly reprogram the metabolic machinery following their uptake by cancer cells. We find that CAF-derived exosomes (CDEs) inhibit mitochondrial oxidative phosphorylation, thereby increasing glycolysis and glutamine-dependent reductive carboxylation in cancer cells. Through 13C-labeled isotope labeling experiments we elucidate that exosomes supply amino acids to nutrient-deprived cancer cells in a mechanism similar to macropinocytosis, albeit without the previously described dependence on oncogenic-Kras signaling. Using intra-exosomal metabolomics, we provide compelling evidence that CDEs contain intact metabolites, including amino acids, lipids, and TCA-cycle intermediates that are avidly utilized by cancer cells for central carbon metabolism and promoting tumor growth under nutrient deprivation or nutrient stressed conditions. DOI: http://dx.doi.org/10.7554/eLife.10250.001 PMID:26920219

Short Carboxylic Acid-Carboxylate Hydrogen Bonds Can Have Fully Localized Protons.

PubMed

Lin, Jiusheng; Pozharski, Edwin; Wilson, Mark A

2017-01-17

Short hydrogen bonds (H-bonds) have been proposed to play key functional roles in several proteins. The location of the proton in short H-bonds is of central importance, as proton delocalization is a defining feature of low-barrier hydrogen bonds (LBHBs). Experimentally determining proton location in H-bonds is challenging. Here, bond length analysis of atomic (1.15-0.98 Å) resolution X-ray crystal structures of the human protein DJ-1 and its bacterial homologue, YajL, was used to determine the protonation states of H-bonded carboxylic acids. DJ-1 contains a buried, dimer-spanning 2.49 Å H-bond between Glu15 and Asp24 that satisfies standard donor-acceptor distance criteria for a LBHB. Bond length analysis indicates that the proton is localized on Asp24, excluding a LBHB at this location. However, similar analysis of the Escherichia coli homologue YajL shows both residues may be protonated at the H-bonded oxygen atoms, potentially consistent with a LBHB. A Protein Data Bank-wide screen identifies candidate carboxylic acid H-bonds in approximately 14% of proteins, which are typically short [⟨d O-O ⟩ = 2.542(2) Å]. Chemically similar H-bonds between hydroxylated residues (Ser/Thr/Tyr) and carboxylates show a trend of lengthening O-O distance with increasing H-bond donor pK a . This trend suggests that conventional electronic effects provide an adequate explanation for short, charge-assisted carboxylic acid-carboxylate H-bonds in proteins, without the need to invoke LBHBs in general. This study demonstrates that bond length analysis of atomic resolution X-ray crystal structures provides a useful experimental test of certain candidate LBHBs.

Intramolecular interactions of L-phenylalanine revealed by inner shell chemical shift

NASA Astrophysics Data System (ADS)

Ganesan, Aravindhan; Wang, Feng

2009-07-01

Intramolecular interactions of the functional groups, carboxylic acid, amino, and phenyl in L-phenylalanine have been revealed through inner shell chemical shift. The chemical shift and electronic structures are studied using its derivatives, 2-phenethylamine (PEA) and 3-phenylpropionic acid (PPA), through substitutions of the functional groups on the chiral carbon Cα, i.e., carboxylic acid (-COOH) and amino (-NH2) groups. Inner shell ionization spectra of L-phenylalanine are simulated using density functional theory based B3LYP/TZVP and LB94/et-pVQZ models, which achieve excellent agreement with the most recently available synchrotron sourced x-ray photoemission spectroscopy of L-phenylalanine (Elettra, Italy). The present study reveals insight into behavior of the peptide bond (CO-NH) through chemical shift of the C1-Cα-Cβ(-Cγ) chain and intramolecular interactions with phenyl. It is found that the chemical shift of the carbonyl C1(=O) site exhibits an apparently redshift (smaller energy) when interacting with the phenyl aromatic group. Removal of the amino group (-NH2) from L-phenylalanine (which forms PPA) brings this energy on C1 close to that in L-alanine (δ <0.01 eV). Chemical environment of Cα and Cβ exhibits more significant differences in L-alanine than in the aromatic species, indicating that the phenyl group indeed affects the peptide bond in the amino acid fragment. No direct evidences are found that the carbonyl acid and amino group interact with the phenyl ring through conventional hydrogen bonds.

Calculated Third Order Rate Constants for Interpreting the Mechanisms of Hydrolyses of Chloroformates, Carboxylic Acid Halides, Sulfonyl Chlorides and Phosphorochloridates

PubMed Central

Bentley, T. William

2015-01-01

Hydrolyses of acid derivatives (e.g., carboxylic acid chlorides and fluorides, fluoro- and chloroformates, sulfonyl chlorides, phosphorochloridates, anhydrides) exhibit pseudo-first order kinetics. Reaction mechanisms vary from those involving a cationic intermediate (SN1) to concerted SN2 processes, and further to third order reactions, in which one solvent molecule acts as the attacking nucleophile and a second molecule acts as a general base catalyst. A unified framework is discussed, in which there are two reaction channels—an SN1-SN2 spectrum and an SN2-SN3 spectrum. Third order rate constants (k3) are calculated for solvolytic reactions in a wide range of compositions of acetone-water mixtures, and are shown to be either approximately constant or correlated with the Grunwald-Winstein Y parameter. These data and kinetic solvent isotope effects, provide the experimental evidence for the SN2-SN3 spectrum (e.g., for chloro- and fluoroformates, chloroacetyl chloride, p-nitrobenzoyl p-toluenesulfonate, sulfonyl chlorides). Deviations from linearity lead to U- or V-shaped plots, which assist in the identification of the point at which the reaction channel changes from SN2-SN3 to SN1-SN2 (e.g., for benzoyl chloride). PMID:26006228

Calculated third order rate constants for interpreting the mechanisms of hydrolyses of chloroformates, carboxylic Acid halides, sulfonyl chlorides and phosphorochloridates.

PubMed

Bentley, T William

2015-05-08

Hydrolyses of acid derivatives (e.g., carboxylic acid chlorides and fluorides, fluoro- and chloroformates, sulfonyl chlorides, phosphorochloridates, anhydrides) exhibit pseudo-first order kinetics. Reaction mechanisms vary from those involving a cationic intermediate (SN1) to concerted SN2 processes, and further to third order reactions, in which one solvent molecule acts as the attacking nucleophile and a second molecule acts as a general base catalyst. A unified framework is discussed, in which there are two reaction channels-an SN1-SN2 spectrum and an SN2-SN3 spectrum. Third order rate constants (k3) are calculated for solvolytic reactions in a wide range of compositions of acetone-water mixtures, and are shown to be either approximately constant or correlated with the Grunwald-Winstein Y parameter. These data and kinetic solvent isotope effects, provide the experimental evidence for the SN2-SN3 spectrum (e.g., for chloro- and fluoroformates, chloroacetyl chloride, p-nitrobenzoyl p-toluenesulfonate, sulfonyl chlorides). Deviations from linearity lead to U- or V-shaped plots, which assist in the identification of the point at which the reaction channel changes from SN2-SN3 to SN1-SN2 (e.g., for benzoyl chloride).

Mechanistic Insights into the Catalytic Oxidation of Carboxylic Acids on Au/TiO 2: Partial Oxidation of Propionic and Butyric Acid to Gold Ketenylidene through Unsaturated Acids

DOE Office of Scientific and Technical Information (OSTI.GOV)

McEntee, Monica; Tang, Wenjie; Neurock, Matthew

Here, the partial oxidation of model C 2–C 4 (acetic, propionic, and butyric) carboxylic acids on Au/TiO 2 catalysts consisting of Au particles ~3 nm in size was investigated using transmission infrared spectroscopy and density functional theory. All three acids readily undergo oxidative dehydrogenation on Au/TiO 2. Propionic and butyric acid dehydrogenate at the C2–C3 positions, whereas acetic acid dehydrogenates at the C1–C2 position. The resulting acrylate and crotonate intermediates are subsequently oxidized to form β-keto acids that decarboxylate. All three acids form a gold ketenylidene intermediate, Au 2C=C=O, along the way to their full oxidation to form CO 2.more » Infrared measurements of Au 2C=C=O formation as a function of time provides a surface spectroscopic probe of the kinetics for the activation and oxidative dehydrogenation of the alkyl groups in the carboxylate intermediates that form.« less

Mechanistic Insights into the Catalytic Oxidation of Carboxylic Acids on Au/TiO 2: Partial Oxidation of Propionic and Butyric Acid to Gold Ketenylidene through Unsaturated Acids

DOE PAGES

McEntee, Monica; Tang, Wenjie; Neurock, Matthew; ...

2014-12-12

Here, the partial oxidation of model C 2–C 4 (acetic, propionic, and butyric) carboxylic acids on Au/TiO 2 catalysts consisting of Au particles ~3 nm in size was investigated using transmission infrared spectroscopy and density functional theory. All three acids readily undergo oxidative dehydrogenation on Au/TiO 2. Propionic and butyric acid dehydrogenate at the C2–C3 positions, whereas acetic acid dehydrogenates at the C1–C2 position. The resulting acrylate and crotonate intermediates are subsequently oxidized to form β-keto acids that decarboxylate. All three acids form a gold ketenylidene intermediate, Au 2C=C=O, along the way to their full oxidation to form CO 2.more » Infrared measurements of Au 2C=C=O formation as a function of time provides a surface spectroscopic probe of the kinetics for the activation and oxidative dehydrogenation of the alkyl groups in the carboxylate intermediates that form.« less

Novel stilbenoids, including cannabispiradienone glycosides, from Tragopogon tommasinii (Asteraceae, Cichorieae) and their potential anti-inflammatory activity.

PubMed

Granica, Sebastian; Piwowarski, Jakub P; Randazzo, Antonio; Schneider, Peter; Żyżyńska-Granica, Barbara; Zidorn, Christian

2015-09-01

A phytochemical investigation of Tragopogon tommasinii Sch.Bip. (Asteraceae, Cichorieae) yielded a total of 21 natural products, two simple phenolic acids (4-hydroxybenzoic acid and p-coumaric acid), four caffeic acid derivatives (chlorogenic acid, 3-O-caffeoylquinic acid, 3,5-O-dicaffeoylquinic acid, and 4,5-O-dicaffeoylquinic acid), six flavonoids (luteolin, luteolin 7-O-glucoside, vitexin, orientin, quercetin 3-O-glucoside, and isorhamnetin 3-O-glucoside), three simple bibenzyls [2-carboxyl-5-hydroxy-3-methoxy-4'-β-glucopyranosyl-oxybibenzyl, 3-caffeoyl-(9→5)-β-apiosyl-(1→6)-β-glucopyranosyloxy-5,4'-dihydroxy-3'-methoxybibenzyl, 3-caffeoyl-(9→5)-β-apiosyl-(1→6)-β-glucopyranosyloxy-4'-dihydroxy-5,3'-dimethoxybibenzyl], three phtalides [3-(4-β-glucopyranosyloxybenzyl)-7-hydroxy-5-methoxyphtalide, 7-β-glucopyranosyloxy-(S)-3-(4-hydroxybenzyl)-5-methoxyphtalide, and 7-(1→6)-α-rhamnosyl-β-glucopyranosyloxy-(S)-3-(4-hydroxybenzyl)-5-methoxyphtalide], two cannabispiradienone derivatives [3-O-β-glucopyranosyldemethoxycannabispiradienone and 3-caffeoyl-(9→5)-β-apiosyl-(1→6)-β-glucopyranosyloxydemethoxycannabispiradienone], and tetra-N-coumaroyl spermine. The three bibenzyls, the latter two benzylphthalides, and both cannabispiradienone derivatives represent new natural compounds and all compounds, except the caffeic acid derivatives and the flavonoids were new for T. tommasinii. The structures were established by HR mass spectrometry, extensive 1D and 2D NMR spectroscopy, and CD spectroscopy. Moreover, the potential anti-inflammatory activities of the new compounds were assayed using human neutrophils and their production of IL-1b, IL-8, TNF-α and MMP-9 as well as the expression of TLR-4, respectively. Copyright © 2015 Elsevier Ltd. All rights reserved.

Microhydration and the Enhanced Acidity of Free Radicals.

PubMed

Walton, John C

2018-02-14

Recent theoretical research employing a continuum solvent model predicted that radical centers would enhance the acidity (RED-shift) of certain proton-donor molecules. Microhydration studies employing a DFT method are reported here with the aim of establishing the effect of the solvent micro-structure on the acidity of radicals with and without RED-shifts. Microhydration cluster structures were obtained for carboxyl, carboxy-ethynyl, carboxy-methyl, and hydroperoxyl radicals. The numbers of water molecules needed to induce spontaneous ionization were determined. The hydration clusters formed primarily round the CO₂ units of the carboxylate-containing radicals. Only 4 or 5 water molecules were needed to induce ionization of carboxyl and carboxy-ethynyl radicals, thus corroborating their large RED-shifts.

Ethylene Production and 1-Aminocyclopropane-1-Carboxylic Acid Conjugation in Thermoinhibited Cicer arietinum L. Seeds 1

PubMed Central

Gallardo, Mercedes; Delgado, María del Mar; Sánchez-Calle, Isabel María; Matilla, Angel Jesús

1991-01-01

The effect of supraoptimal temperatures (30°C, 35°C) on germination and ethylene production of Cicer arietinum (chick-pea) seeds was measured. Compared with a 25°C control, these temperatures inhibited both germination and ethylene production. The effect of supraoptimal temperatures could be alleviated by treating the seeds with ethylene. It was concluded that one effect of high temperature on germination was due to its negative effect on ethylene production. This inhibitory effect of high temperature was due to increased conjugation of 1-aminocyclopropane-1-carboxylic acid to 1-(malonylamino)cyclopropane-1-carboxylic acid and to an inhibition of ethylene-forming enzyme activity. PMID:16668358

Electrocarboxylation: towards sustainable and efficient synthesis of valuable carboxylic acids

PubMed Central

Matthessen, Roman; Fransaer, Jan; Binnemans, Koen

2014-01-01

Summary The near-unlimited availability of CO2 has stimulated a growing research effort in creating value-added products from this greenhouse gas. This paper presents the trends on the most important methods used in the electrochemical synthesis of carboxylic acids from carbon dioxide. An overview is given of different substrate groups which form carboxylic acids upon CO2 fixation, including mechanistic considerations. While most work focuses on the electrocarboxylation of substrates with sacrificial anodes, this review considers the possibilities and challenges of implementing other synthetic methodologies. In view of potential industrial application, the choice of reactor setup, electrode type and reaction pathway has a large influence on the sustainability and efficiency of the process. PMID:25383120

Determination of the asphaltene and carboxylic acid content of a heavy oil using a microfluidic device.

PubMed

Bowden, Stephen A; Wilson, Rab; Parnell, John; Cooper, Jonathan M

2009-03-21

Heavy oil utilisation is set to increase over the coming decades as reserves of conventional oil decline. Heavy oil differs from conventional oil in containing relatively large quantities of asphaltene and carboxylic acids. The proportions of these compounds greatly influence how oil behaves during production and its utilisation as a fuel or feedstock. We report the development of a microfluidic technique, based on a H-cell, that can extract the carboxylic acid components of an oil and assess its asphaltene content. Ultimately this technology could yield a field-deployable device capable of performing measurements that facilitate improved resource management at the point of resource-extraction.

High fluorescence emission of carboxylic acid functionalized polystyrene/BaTiO{sub 3} nanocomposites and rare earth metal complexes: Preparation and characterization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cao, X. T.; Showkat, A. M.; Wang, Z.

2015-03-30

Noble fluorescence nanocomposite compound based on barium titanate nanoparticles (BTO), polystyrene (PSt), and terbium ion (Tb{sup 3+}) was synthesized by a combination of surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization, Friedel-Crafts alkylation reaction and coordinate chemistry. Initially, a modification of surface of BTO was conducted by an exchange process with S-benzyl S’-trimethoxysilylpropyltrithiocarbonate to create macro-initiator for polymerization of styrene. Subsequently, aryl carboxylic acid functionalized polystyrene grafted barium titanate (BTO-g-PSt-COOH) was generated by substitution reaction between 4-(Chloromethyl) benzoic acid and PSt chains. The coordination of the nanohybrids with Tb{sup 3+} ions afforded fluorescent Tb{sup 3+} tagged aryl carboxylic acid functionalized polystyrenemore » grafted barium titanate (BTO-g-PSt-Tb{sup 3+}) complexes. Structure, morphology, and fluorescence properties of nanohybrid complexes were investigated by respective physical and spectral studies. FT-IR and SEM analyses confirmed the formation of BTO-g-PSt-Tb{sup 3+}nanohybrids. Furthermore, TGA profiles demonstrated the grafting of aryl carboxylic acid functionalized polystyrene on BTO surface. Optical properties of BTO-g-PSt-Tb{sup 3+} complexes were investigated by fluorescence spectroscopy.« less

Method for the determination of carboxylic acids in industrial effluents using dispersive liquid-liquid microextraction with injection port derivatization gas chromatography-mass spectrometry.

PubMed

Makoś, Patrycja; Fernandes, Andre; Boczkaj, Grzegorz

2017-09-29

The paper presents a new method for the determination of 15 carboxylic acids in samples of postoxidative effluents from the production of petroleum bitumens using ion-pair dispersive liquid-liquid microextraction and gas chromatography coupled to mass spectrometry with injection port derivatization. Several parameters related to the extraction and derivatization efficiency were optimized. Under optimized experimental conditions, the obtained limit of detection and quantification ranged from 0.0069 to 1.12μg/mL and 0.014 to 2.24μg/mL, respectively. The precision (RSD ranged 1.29-6.42%) and recovery (69.43-125.79%) were satisfactory. Nine carboxylic acids at concentrations ranging from 0.10μg/mL to 15.06μg/mL were determined in the raw wastewater and in samples of effluents treated by various oxidation methods. The studies revealed a substantial increase of concentration of benzoic acids, in samples of wastewater after treatment, which confirms the need of carboxylic acids monitoring during industrial effluent treatment processes. Copyright © 2017 Elsevier B.V. All rights reserved.

A new method to synthesize creatine derivatives.

PubMed

Garbati, Patrizia; Salis, Annalisa; Adriano, Enrico; Galatini, Andrea; Damonte, Gianluca; Balestrino, Maurizio; Millo, Enrico

2013-10-01

Creatine is an amino acid that has a pivotal role in energy metabolism of cells. Creatine acts as an "ATP shuttle", carrying ATP to the sites where it is utilized, through its reversible phosphorylation by creatine kinase. Moreover, the creatine-phosphocreatine system delays ATP depletion during anoxia or ischemia, thus exerting a neuroprotective role during those pathological conditions. Thus, its administration has been advocated as a treatment or prevention of several conditions involving the central nervous system. However, creatine crosses poorly the blood-brain barrier and the cell plasma membrane, thus its administration has but a limited effect. The use of more lipophilic creatine derivatives has thus been suggested. However, such a synthesis is complicated by the intrinsic characteristics of the creatine molecule that hardly reacts with other molecules and easily cyclizes to creatinine. We obtained amide derivatives from creatine starting from a new protected creatine molecule synthesized by us, the so-called (Boc)2-creatine. We used a temporary protection only on the creatine guanidine group while allowing a good reactivity on the carboxylic group. This temporary protection ensured efficient creatine dissolution in organic solvents and offered simultaneous protection of creatine toward intramolecular cyclization to creatinine. In this manner, it was possible to selectively conjugate molecules on the carboxylic group. The creatine guanidine group was easily released from the protection at the end of the reaction, thus obtaining the desired creatine derivative.

Polyimide foam for the thermal insulation and fire protection

NASA Technical Reports Server (NTRS)

Rosser, R. W. (Inventor)

1973-01-01

The preparation of chemically resistant and flame retardant foams from polyfunctional aromatic carboxylic acid derivatives and organic polyisocyanates is outlined. It was found that polyimide foams of reproducible density above 1 lb./ft. and below 6 lbs./cu ft. can be obtained by employing in the reaction of least 2% by weight of siloxane-glycol copolymer as a surfactant which acts as a specific density control agent. Polyimide foams into which reinforcing fibers such as silicon dioxide and carbon fibers may be incorporated were also produced.

Facile access to 2-acyloxy-, aryloxy- and alkenyloxy-2H-azirines via an SN2'-SN2' cascade in 2-halo-2H-azirines.

PubMed

Rostovskii, Nikolai V; Smetanin, Ilia A; Agafonova, Anastasiya V; Sakharov, Pavel A; Ruvinskaya, Julia O; Khlebnikov, Alexander F; Novikov, Mikhail S

2018-05-02

Various 2-oxygen-substituted 2H-azirine-2-carboxylic acid derivatives were synthesized in high yields under mild conditions from readily available precursors, 2-halo-2H-azirines and OH-reagents having pKa values in the range of 3-10. This reaction is the first example of substitution at the azirine carbon atom for which an unusual SN2'-SN2' cascade mechanism was revealed.

Dinuclear Zinc-Prophenol-Catalyzed Enantioselective α-Hydroxyacetate Aldol Reaction with Activated Ester Equivalents

PubMed Central

Trost, Barry M.; Michaelis, David J.; Truica, Mihai I.

2013-01-01

An enantioselective α-hydroxyacetate aldol reaction that employs N-acetyl pyrroles as activated ester equivalents and generates syn 1,2-diols in good yield and diastereoselectivity is reported. This dinuclear zinc Prophenol-catalyzed transformation proceeds with high enantioselectivity with a wide variety of substrates including aryl, alyl, and alkenyl aldehydes. The resulting α,β-dihydroxy activated esters are versatile intermediates for the synthesis of a variety of carboxylic acid derivatives including amides, esters, and unsymmetrical ketones. PMID:23947595

In silico prediction of acyl glucuronide reactivity

NASA Astrophysics Data System (ADS)

Potter, Tim; Lewis, Richard; Luker, Tim; Bonnert, Roger; Bernstein, Michael A.; Birkinshaw, Timothy N.; Thom, Stephen; Wenlock, Mark; Paine, Stuart

2011-11-01

Drugs and drug candidates containing a carboxylic acid moiety, including many widely used non-steroidal anti-inflammatory drugs (NSAIDs) are often metabolized to form acyl glucuronides (AGs). NSAIDs such as Ibuprofen are amongst the most widely used drugs on the market, whereas similar carboxylic acid drugs such as Suprofen have been withdrawn due to adverse events. Although the link between these AG metabolites and toxicity is not proven, there is circumstantial literature evidence to suggest that more reactive acyl glucuronides may, in some cases, present a greater risk of exhibiting toxic effects. We wished therefore to rank the reactivity of potential new carboxylate-containing drug candidates, and performed kinetic studies on synthetic acyl glucuronides to benchmark our key compounds. Driven by the desire to quickly rank the reactivity of compounds without the need for lengthy synthesis of the acyl glucuronide, a correlation was established between the degradation half-life of the acyl glucuronide and the half life for the hydrolysis of the more readily available methyl ester derivative. This finding enabled a considerable broadening of chemical property space to be investigated. The need for kinetic measurements was subsequently eliminated altogether by correlating the methyl ester hydrolysis half-life with the predicted 13C NMR chemical shift of the carbonyl carbon together with readily available steric descriptors in a PLS model. This completely in silico prediction of acyl glucuronide reactivity is applicable within the earliest stages of drug design with low cost and acceptable accuracy to guide intelligent molecular design. This reactivity data will be useful alongside the more complex additional pharmacokinetic exposure and distribution data that is generated later in the drug discovery process for assessing the overall toxicological risk of acidic drugs.

A new alkaloid from Portulaca oleracea L. and its antiacetylcholinesterase activity.

PubMed

Xiu, Fen; Li, Xuetao; Zhang, Wenjie; He, Fan; Ying, Xixiang; Stien, Didier

2018-04-18

A new alkaloid, (10E, 12E)-9-ureidooctadeca-10, 12-dienoic acid, named oleraurea (1) and 10 known compounds, p-hydroxybenzaldehyde (2), p-hydroxybenzoic acid (3), p-hydroxyacetophenone (4), benzamide (5), (E)-p-coumaramide (6), (E)-ferulamide (7), soyalkaloid A (8), β-carboline-3-carboxylic acid (9), 2, 3, 4, 9-tetrahydro-1H-pyrido [3, 4-b] indole-3-carboxylic acid (10), (1S, 3S)-1-methyl-1, 2, 3, 4-tetrahydro-β-carboline-3-carboxylic acid (11) were obtained from Portulaca oleracea L., in which, compounds 4, 5, 8-11 were isolated from the plant for the first time. The structure of the compound 1 was identified using spectroscopic methods including 1D and 2D NMR, HR-ESI-TOF-MS. The compounds 1, 5-11 presented anticholinesterase activities, but the P. oleracea extract (POE) presented very low anticholinesterase activity.

Sulfonated reduced graphene oxide as a highly efficient catalyst for direct amidation of carboxylic acids with amines using ultrasonic irradiation.

PubMed

Mirza-Aghayan, Maryam; Tavana, Mahdieh Molaee; Boukherroub, Rabah

2016-03-01

Sulfonated reduced graphene oxide nanosheets (rGO-SO3H) were prepared by grafting sulfonic acid-containing aryl radicals onto chemically reduced graphene oxide (rGO) under sonochemical conditions. rGO-SO3H catalyst was characterized by Fourier-transform infrared (FT-IR) spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-ray photoelectron spectroscopy (XPS). rGO-SO3H catalyst was successfully applied as a reusable solid acid catalyst for the direct amidation of carboxylic acids with amines into the corresponding amides under ultrasonic irradiation. The direct sonochemical amidation of carboxylic acid takes place under mild conditions affording in good to high yields (56-95%) the corresponding amides in short reaction times. Copyright © 2015 Elsevier B.V. All rights reserved.

Tailored and integrated production of carboxylated cellulose nanocrystals (CNC) with nanofibrils (CNF) through maleic acid hydrolysis

Treesearch

Ruibin Wang; Liheng Chen; J.Y. Zhu; Rendang Yang

2017-01-01

This study demonstrates the feasibility of tailored and integrated production of carboxylated cellulose nanocrystals (CNC) with nanofibrils (CNF) from bleached pulp fibers through hydrolysis using a recyclable dicarboxylic acid. Hydrolysis experiments were conducted using ranges of 15–75 wt% maleic acid concentrations, 60–120°C temperatures, and 5–300 min reaction...

Chemo-enzymatic Baeyer-Villiger oxidation of 4-methylcyclohexanone via kinetic resolution of racemic carboxylic acids: direct access to enantioenriched lactone.

PubMed

Drożdż, Agnieszka; Chrobok, Anna

2016-01-21

A new method for the asymmetric chemo-enzymatic Baeyer-Villiger oxidation of prochiral 4-methylcyclohexanone to (R)-4-methylcaprolactone in the presence of (±)-4-methyloctanoic acid, Candida Antarctica lipase B and 30% aq. H2O2 has been developed. A mechanism for the asymmetric induction based on kinetic resolution of racemic carboxylic acids is proposed.

Development and optimization of the synthesis of new thiazolidin-4-one derivatives of ibuprofen.

PubMed

Vasincu, Ioana; Apotrosoaei, Maria; Panzariu, Andreea; Buron, F; Routier, S; Profire, Lenuta

2014-01-01

Ibuprofen, an important nonsteroidal anti-inflammatory agent, is one of the most prescribed drugs for the treatment of pain and inflammation from various rheumatic diseases, but some side effects can occur on long-term use. The method for synthesis optimization of new derivatives of Ibuprofen with thiazolidin-4-one moiety, with improved pharmacological and toxicological profile. To optimize the derivatization method of free carboxyl group of Ibuprofen (2-(4-isobutylphenyl)propionic acid) the reaction conditions were varied (reagent ratio, catalyst, reaction medium). The most favorable method was proved to be the reaction between ibuprofen hydrazone and mercaptoacetic acid, in excess, at 80-85 degrees C, for 6 h with 96% conversion rate. The synthesis of 2-phenyl-3-[2-(4-(isobutyl)phenyl)-2-methyl]acetamido-thiazolidin-4-one derivative was optimized in view of applying it as a general procedure for the synthesis of other derivatives with related structure. The chemical structure and molecular weight of the synthesized compound were confirmed by spectral methods (IR, 1H NMR, 13C NMR, HR-MS).

1-Azaniumylcyclobutane-1-carboxylate monohydrate

NASA Technical Reports Server (NTRS)

Butcher, Ray J.; Brewer, Greg; Burton, Aaron S.; Dworkin, Jason

2014-01-01

In the title compound, C5H9NO2H2O, the amino acid is in the usual zwitterionic form involving the carboxylate group. The cyclobutane backbone of the amino acid is disordered over two conformations, with occupancies of 0.882 (7) and0.118 (7). In the crystal, NH O and OH O hydrogen bonds link the zwitterions [with the water molecule involved as both acceptor (with the NH3+) and donor (through a single carboxylate O from two different aminocyclobutane carboxylatemoities)], resulting in a two-dimensional layered structure lying parallel to (100).